@article{LangerBerndtSchreiner, author = {Langer, Christoph and Berndt, Dominik and Schreiner, Rupert}, title = {Sensitivity of thermal conductivity vacuum gauges for constant current and constant temperature operation}, series = {Journal of Vacuum Science and Technology B: Nanotechnology and Microelectronics}, volume = {40}, journal = {Journal of Vacuum Science and Technology B: Nanotechnology and Microelectronics}, number = {5}, publisher = {AIP Publishing}, doi = {10.1116/6.0001964}, abstract = {To optimize the measurement range of thermal conductivity vacuum gauges, an expression for the sensitivity is required that takes into account all geometrical, material-specific, and operating parameters. Therefore, equations of the sensor output signal as a function of the pressure for the constant current and the constant temperature mode have been developed analytically. Based on these equations, the sensitivity of the vacuum gauge and its influencing parameters was investigated and discussed. For comparable conditions, the constant temperature operation shows a significantly higher sensitivity for high pressures, while the constant current operation shows higher sensitivity at low pressures. The sensitivity in both the constant current and the constant temperature mode depends on the ratio of the filament surface area and the parasitic thermal conductance. In addition, for the constant current operation, the sensitivity also depends on the current value and the temperature coefficient of the filament resistor. For the constant temperature operation, the sensitivity additionally depends on the distance of the filament and the reference plane. However, to extend the measurement range of a thermal conductivity vacuum gauge toward low pressures, a reduction of the parasitic thermal conductance is mandatory for both the constant current and the constant temperature mode.}, language = {en} } @inproceedings{DamsPrommesbergerSchreiner, author = {Dams, Florian and Prommesberger, Christian and Schreiner, Rupert}, title = {Fabrication process of silicon-tip-arrays for field emission applications}, series = {24th International Vacuum Nanoelectronics Conference (IVNC), 2011 : 18 - 22 July 2011, Historische Stadthalle Wuppertal, Germany}, booktitle = {24th International Vacuum Nanoelectronics Conference (IVNC), 2011 : 18 - 22 July 2011, Historische Stadthalle Wuppertal, Germany}, publisher = {IEEE}, isbn = {978-3-00-035081-8}, issn = {2380-6311}, pages = {49 -- 50}, abstract = {A micromachined process to assemble homogeneous and reproducible tip arrays for field emission applications is developed and characterized. As substrate material p- as well as n-doped silicon is used. Lateral position of the tips is defined by structuring silicon dioxide to discs in a photolithographic process. Vertical structure of the tips is defined by a combination of RIE dry etching with controlled anisotropy and thermally oxidization of silicon in order to sharpen the tips. Hence field emitter arrays (FEAs) can be assembled both as bare and coated cathodes. To assemble field emission diodes, this fabrication process allows placing a metal anode in a micrometer order distance to the tips by a self-aligning procedure. The anode is placed in an evaporation process whereupon sharpening oxide is used as isolator between anode and cathode. Electrical characterization of the cathodes showed very good homogeneity, well alignment and stability over time of emission current from all tips (i.e. 100\% efficiency).}, language = {en} } @unpublished{RueckMuellerJobstetal., author = {R{\"u}ck, Thomas and M{\"u}ller, Max and Jobst, Simon and Weigl, Stefan and Pangerl, Jonas and Bierl, Rudolf and Matysik, Frank-Michael}, title = {Digital Twin of a Photoacoustic Trace Gas Sensor for Monitoring Methane in Complex Gas Compositions}, publisher = {Elsevier / SSRN}, doi = {10.2139/ssrn.4215170}, pages = {22}, abstract = {The digitalization of industrial processes requires smart sensor systems. Photoacoustic spectroscopy is well suited for this purpose as it allows for small-sized and low-cost trace gas analysis. However, the method is susceptible to changes in measurement conditions and standard calibration routines often fail to correct for all changes. We therefore created a Digital Twin (DT) of a photoacoustic trace gas sensor for methane and evaluated it regarding variations in gas composition (CH4, N2, O2, CO2, H2O), temperature and pressure. With a mean absolute percentage error of 0.8 \% the accuracy of the sensor after DT compensation significantly exceeds the 24 \% achieved based on standard calibration in nitrogen. For the first time, we can fully analytically compute the photoacoustic signal under moderate ambient conditions with an error in the ppbV range by taking a holistic approach. Assuming knowledge of the underlying energy transfer processes, the model of this Digital Twin can be adapted to any microphone based photoacoustic sensor for monitoring any analyte species.}, language = {en} } @article{SchuezDraegerRichteretal., author = {Sch{\"u}z, B. and Dr{\"a}ger, D. and Richter, Stefanie and Kummer, K. and Kuhlmey, Adelheid and Tesch-R{\"o}mer, C.}, title = {Autonomie trotz Multimorbidit{\"a}t im Alter - Der Berliner Forschungsverbund AMA}, series = {Zeitschrift f{\"u}r Gerontologie und Geriatrie}, journal = {Zeitschrift f{\"u}r Gerontologie und Geriatrie}, number = {Sonderheft 2}, publisher = {Springer}, pages = {9 -- 25}, abstract = {Mit zunehmendem Alter steigt der Anteil mehrfach erkrankter Menschen und immer mehr Menschen erreichen ein sehr hohes Lebensalter. Trotz des medizinischen Fortschritts und verbesserter Lebenslagen m{\"u}ssen viele alte Menschen k{\"o}rperliche, psychische und soziale Einschr{\"a}nkungen bew{\"a}ltigen. Es ist eine große gesundheits- und sozialpolitische Herausforderung, diese alten Frauen und M{\"a}nner mit gesundheitlichen Beeintr{\"a}chtigungen in ihrem Bestreben nach einer weitestgehend autonomen Lebensgestaltung zu unterst{\"u}tzen und zu st{\"a}rken. Vor diesem Hintergrund widmete sich der Forschungsverbund „Autonomie trotz Multimorbidit{\"a}t im Alter" (AMA I) der Leitfrage, inwieweit eine selbstbestimmte Lebensgestaltung alter mehrfach erkrankter Menschen erhalten werden kann. Um der Vielfalt der Lebenswelten {\"a}lterer Menschen gerecht zu werden, wurden im Alltag wenig eingeschr{\"a}nkte und pflegebed{\"u}rftige sowie kognitiv beeintr{\"a}chtigte Personen in die Untersuchung einbezogen. Darunter waren Frauen und M{\"a}nner, die noch im eigenen Haushalt und solche die im Pflegeheim lebten. Im Fokus der Untersuchungen standen die Ressourcen, die den alten Menschen in ihrer jeweiligen Lebenssituation zur Verf{\"u}gung standen und die Frage, wie diese gest{\"a}rkt werden k{\"o}nnen. Der Beitrag pr{\"a}sentiert Ergebnisse zu dieser Forschungsfrage aus der 1. F{\"o}rderphase des AMA-Verbundes. Darauf aufbauend werden in einer 2. F{\"o}rderphase (2011-2013, AMA II) nunmehr nachhaltige praxisrelevante Interventionen zur Mobilisierung von autonomierelevanten Ressourcen mehrfach erkrankter alter Menschen entwickelt und auf ihre Praxistauglichkeit getestet.}, language = {de} } @article{ScheidtNaveRichterFuchsetal., author = {Scheidt-Nave, Christa and Richter, Stefanie and Fuchs, Judith and Kuhlmey, Adelheid}, title = {Herausforderungen an die Gesundheitsforschung f{\"u}r eine alternde Gesellschaft am Beispiel "Multimorbidit{\"a}t"}, series = {Bundesgesundheitsblatt - Gesundheitsforschung - Gesundheitsschutz}, volume = {53}, journal = {Bundesgesundheitsblatt - Gesundheitsforschung - Gesundheitsschutz}, number = {5}, pages = {441 -- 450}, abstract = {Indem ein wachsender Anteil der Bev{\"o}lkerung ein hohes Alter erreicht, {\"a}ndern sich Krankheitsspektrum und Versorgungsbedarf. Besondere Herausforderungen f{\"u}r das Gesundheitssystem ergeben sich durch Mehrfacherkrankung (Multimorbidit{\"a}t) {\"a}lterer Menschen. Im Gegensatz zu krankheitsspezifischen Endpunkten treten Funktion im Alltag und subjektive Ergebnisdimensionen wie selbstbestimmte Lebensf{\"u}hrung (Autonomie), soziale Teilhabe und Lebensqualit{\"a}t als Pr{\"a}ventions- und Behandlungsziel in den Vordergrund. Die Gesundheitsforschung hat die Aufgabe, auf die Bed{\"u}rfnisse spezifischer Zielgruppen alter Menschen abgestimmte Pr{\"a}ventions- und Versorgungsmodelle zu entwickeln. Entscheidend dabei ist die St{\"a}rkung von personalen, sozialen und organisatorischen Ressourcen. Voraussetzung hierf{\"u}r sind genaue Kenntnisse zur Entwicklung und zum Verlauf des Krankheitsgeschehens und zu zentralen Einflussfaktoren auf der Grundlage epidemiologischer Beobachtungsstudien. Gezielte Maßnahmen sind in Interventions- und Evaluationsstudien auf Wirksamkeit, Wirkung und Wirtschaftlichkeit zu {\"u}berpr{\"u}fen. Der vom Bundesministerium f{\"u}r Bildung und Forschung (BMBF) initiierte F{\"o}rderungsschwerpunkt „Gesundheit im Alter" f{\"o}rdert insgesamt sechs Forschungsverb{\"u}nde zum Thema Multimorbidit{\"a}t, die hier kurz vorgestellt werden.}, language = {de} } @incollection{RichterKuhlmey, author = {Richter, Stefanie and Kuhlmey, Adelheid}, title = {Alter, Altern und Gesundheit als Herausforderung f{\"u}r Forschung in Verbundzusammenh{\"a}ngen}, series = {Autonomie trotz Multimorbidit{\"a}t}, booktitle = {Autonomie trotz Multimorbidit{\"a}t}, editor = {Tesch-R{\"o}mer, Clemens}, publisher = {Hogrefe}, pages = {203 -- 220}, abstract = {Angesichts der zunehmenden Alterung der Bev{\"o}lkerung wird die Frage nach dem Erhalt von Autonomie alter Menschen trotz Mehrfacherkrankungen immer brisanter. Die Beitr{\"a}ge in diesem Band besch{\"a}ftigen sich mit der Frage, wie alte Menschen trotz Multimorbidit{\"a}t und Gesundheitseinbußen autonom und selbstbestimmt leben k{\"o}nnen.Die Autoren pr{\"a}sentieren Befunde, die den Entwicklungsstand altersangemessener, zielgruppenspezifischer Instrumente sowie Zugangswege zur Erfassung von Multimorbidit{\"a}t und Autonomie aufzeigen. Weitere Beitr{\"a}ge thematisieren u.a. personale, preofessionelle und sozial-r{\"a}umliche Faktoren, die Autonomie angesichts von Multimorbidit{\"a}t unterst{\"u}tzen und als Ressourcen wirken. Wie diese Ressourcen einzeln und in ihrer Wechselbeziehung zum Autonomieerhalt beitragen, wie sie erhalten und gef{\"o}rdert werden k{\"o}nnen, wird beispielhaft im Kontext komplexer autonomierelevanter Gesundheitsprobleme wie Schmerz, Sturz- und Schlafst{\"o}rungen gezeigt.}, language = {de} } @article{RichterFlickKuhlmey, author = {Richter, Stefanie and Flick, Uwe and Kuhlmey, Adelheid}, title = {Alter(n) und Gesundheit. Chancen und H{\"u}rden einer disziplinen{\"u}bergreifenden Zusammenarbeit}, series = {G+G Wissenschaft}, volume = {11}, journal = {G+G Wissenschaft}, number = {2}, publisher = {GGW}, pages = {7 -- 15}, abstract = {Eine umfassende theoretische und empirische Auseinandersetzung mit Fragestellungen und Problemen des Alter(n)s setzt eine inter- beziehungsweise transdisziplin{\"a}re Wissenschaftspraxis voraus. Deren Realisierung st{\"o}ßt allerdings immer wieder an Grenzen, denn eine disziplinen{\"u}bergreifende Zusammenarbeit steht einem Wissenschaftssystem gegen{\"u}ber, dem Ausdifferenzierung, Abgrenzung, Spezialisierung und die Bildung disziplinenspezifischer Kulturen anhaften. Hinzu kommen Publikationsstrukturen mit den Regeln eines akademischen Karrieremarktes, der eine enge (sub)disziplin{\"a}re Fokussierung belohnt. Der Beitrag beleuchtet die Probleme und L{\"o}sungsstrategien der disziplinen{\"u}bergreifenden Zusammenarbeit in der Gerontologie am Beispiel des Forschungsverbundes "Gesundheit im Alter"}, language = {de} } @inproceedings{MuellerRueckJobstetal., author = {M{\"u}ller, Max and R{\"u}ck, Thomas and Jobst, Simon and Pangerl, Jonas and Bierl, Rudolf and Matysik, Frank-Michael}, title = {Creating a Digital Twin of a Photoacoustic Gas Sensor for Methane Detection in Complex Gas Matrices}, series = {Proceedings Optical Sensors and Sensing Congress 2022 (AIS, LACSEA, Sensors, ES): 11-15 July 2022, Vancouver, British Columbia, Canada}, booktitle = {Proceedings Optical Sensors and Sensing Congress 2022 (AIS, LACSEA, Sensors, ES): 11-15 July 2022, Vancouver, British Columbia, Canada}, publisher = {Optica Publishing Group}, isbn = {978-1-957171-10-4}, doi = {10.1364/LACSEA.2022.LW4D.2}, abstract = {We present the calculation results from a digital twin (DT) of our photoacoustic (PA) sensor for methane detection, regarding gas composition, temperature and pressure variations.}, language = {en} } @article{PeterHolsteynsDalmeretal., author = {Peter, Daniel and Holsteyns, Frank and Dalmer, Michael and Kruwinus, Hans and Lechner, Alfred and Bensch, Wolfgang}, title = {A Study on the Structure Collapse Mechanisms for High Aspect Ratio Structures with Application to Clean Processing}, series = {ECS Meeting Abstracts}, volume = {MA2009-02}, journal = {ECS Meeting Abstracts}, number = {24}, publisher = {IOP Science}, doi = {10.1149/MA2009-02/24/2084}, language = {en} } @incollection{Skornia, author = {Skornia, Christoph}, title = {Sicherheit in der Cloud}, series = {IT-Sicherheit}, booktitle = {IT-Sicherheit}, editor = {Lang, Michael and L{\"o}hr, Hans and Angermeier, Daniel}, publisher = {Hanser}, address = {M{\"u}nchen}, isbn = {978-3-446-47223-5}, doi = {10.3139/9783446473478.015}, pages = {263 -- 278}, language = {de} } @inproceedings{SchreinerMulotWiedmannetal., author = {Schreiner, Rupert and Mulot, M. and Wiedmann, J{\"o}rg and Coenning, W. and Porsche, J. and Gentner, Jean-Louis and Berroth, Manfred and Scholz, Ferdinand and Schwizer, H.}, title = {Dynamic measurements on narrow linewidth complex coupled 1.55 μm DFB lasers with gain and index grating in antiphase}, series = {Conference Proceedings. Eleventh International Conference on Indium Phosphide and Related Materials (IPRM'99), 16-20 May 1999, Davos, Switzerland}, booktitle = {Conference Proceedings. Eleventh International Conference on Indium Phosphide and Related Materials (IPRM'99), 16-20 May 1999, Davos, Switzerland}, publisher = {IEEE}, address = {Piscataway}, isbn = {0-7803-5562-8}, doi = {10.1109/ICIPRM.1999.773626}, pages = {25 -- 28}, abstract = {We report on dynamic measurements on antiphase complex coupled 1.55 /spl mu/m DFB lasers. The antiphase complex coupling mechanism is realized by periodically etching the active layer and quarternary InGaAsP overgrowth. This new fabrication approach results in very narrow linewidths measured on devices with rather short resonator lengths. The minimum linewidth for a 375 /spl mu/m long ridge waveguide laser was only 250 kHz at an optical output power of 4 mW. The RC-limited 3dB-bandwidth for those devices was /spl sim/6 GHz. Using circuit model corrections, the intrinsic bandwidth limitation of those lasers was found to be 17.4 GHz.}, language = {en} } @inproceedings{SchreinerNaegeleKoerbletal., author = {Schreiner, Rupert and Naegele, Peter and Koerbl, Michael and Groening, Albert and Gentner, Jean-Louis and Schweizer, Heinz C.}, title = {Monolithically integrated tunable laterally-coupled distributed feedback lasers with self-aligned Ti/Pt/Au ohmic contacts}, series = {Proceedings Volume 4871, Semiconductor Lasers and Optical Amplifiers for Lightwave Communication SystemsSemiconductor Lasers and Optical Amplifiers for Lightwave Communication Systems}, booktitle = {Proceedings Volume 4871, Semiconductor Lasers and Optical Amplifiers for Lightwave Communication SystemsSemiconductor Lasers and Optical Amplifiers for Lightwave Communication Systems}, editor = {Mirin, Richard P. and Menoni, Carmen S.}, publisher = {SPIE}, doi = {10.1117/12.457281}, pages = {160}, abstract = {We present a new method for fabrication of tunable InGaAsP-InP single mode lasers without epitaxial overgrowth. These devices show the advantage of a considerably simplified fabrication process compared to conventional tunable laser types. The lasers comprise an active Bragg reflector integrated with an uncorrugated separately pumped gain region. To overcome the extensive and expensive overgrowth step we realized a surface grating on both sides of the ridge mesa, which provides DFB operation. By adjusting the current through the Bragg reflector, the wavelength can be tuned between 1590.8 nm and 1595.2 nm. A maximum of 11 wavelength channels with an average spacing of ~0.5 nm and a constant optical output power of ~0.5 mW are addressable.}, language = {en} } @article{CheongAwKarimovetal., author = {Cheong, Kuan Yew and Aw, Kean and Karimov, Khasan S. and Zhao, Feng and Mahroof-Tahir, Mohammad and Schreiner, Rupert}, title = {Advances in Smart Materials and Applications}, series = {Advances in Materials Science and Engineering}, journal = {Advances in Materials Science and Engineering}, publisher = {Hindawi}, doi = {10.1155/2014/517342}, abstract = {This is one of a series of special issues published in Advances in Materials Science and Engineering, focusing on the latest advances of smart materials and their applications. Evolution of engineering materials is strongly depending on the growing transformation of complexity in engineering products. New materials being designed are required to provide specific properties and demonstrate certain functional characteristics by manipulating their dimension, chemistry, and structure through various advanced technologies. Therefore, "smartness" of a material has become the topic of interest. Properties of smart materials may change accordingly to the applied external stimuli. Under the direction of the editorial team, we showcase advances of organic and inorganic based smart materials and their applications in areas of specific interest such as energy, environment, and health. A total of 9 articles are published in this special issue. Six articles are focused on production, synthesis, and optimization of smart materials; and the remaining are dedicated to application of smart materials.}, language = {en} } @inproceedings{SaravananGerlachPeschkeetal., author = {Saravanan, Brem Kumar and Gerlach, Philipp and Peschke, Martin and Knoedl, Thomas and Schreiner, Rupert and Hanke, Christian and Stegmueller, Bernhard}, title = {Integrated DFB laser electro-absorption modulator based on identical MQW-double stack active layer for high-speed modulation beyond 10 GBIT/S}, series = {16th IPRM. 2004 International Conference on Indium Phosphide and Related Materials, 31 May - 04 June 2004, Kagoshima, Japan}, booktitle = {16th IPRM. 2004 International Conference on Indium Phosphide and Related Materials, 31 May - 04 June 2004, Kagoshima, Japan}, publisher = {IEEE}, isbn = {0-7803-8595-0}, doi = {10.1109/ICIPRM.2004.1442656}, pages = {236 -- 238}, abstract = {Integrated DFBLD-EAM-SOA devices utilizing an identical MQW active region have been realized in the AlGaInAs/InP material system. A fiber-coupled optical power of >6 mW with a 10 dB static extinction, 44 dB SMSR single-mode spectrum and a 3 dBe cutoff frequency of 25 GHz was measured.}, language = {en} } @article{ZahnerSchreinerStierstorferetal., author = {Zahner, Th and Schreiner, Rupert and Stierstorfer, R. and Kus, O. and Li, S. T. and Roessler, R. and Pedarnig, J. D. and B{\"a}uerle, D. and Lengfellner, H.}, title = {Off-diagonal Seebeck effect and anisotropic thermopower in Bi2Sr2CaCu2O8 thin films}, series = {Europhysics Letters}, volume = {40}, journal = {Europhysics Letters}, number = {6}, publisher = {IOP Sciences}, doi = {10.1209/epl/i1997-00521-4}, pages = {673 -- 678}, abstract = {The anisotropy ΔS of the thermopower in thin films of the high-Tc superconductor Bi2Sr2CaCu2O8 is investigated using off-c-axis epitaxial film growth and the off-diagonal Seebeck effect. The measurements represent a new method for the investigation of anisotropic transport properties in solids, taking advantage of the availability of oriented grown crystalline thin films instead of using bulk crystals. First results for the temperature dependence ΔS(T) in Bi2Sr2CaCu2O8 thin films are presented and described within a two-band model. Subjecting the films to heat treatments in different gases at relatively low temperatures, ΔS could reversibly be changed in a wide range.}, language = {en} } @inproceedings{KnodlHankeSaravananetal., author = {Knodl, Thomas and Hanke, Christian and Saravanan, Brem Kumar and Peschke, Martin and Schreiner, Rupert and Stegmuller, Bernhard}, title = {Integrated 1.3-μm InGaAlAs-InP laser-modulator with double-stack MQW layer structure}, series = {Proceedings Volume 5451, Integrated Optics and Photonic Integrated Circuits}, booktitle = {Proceedings Volume 5451, Integrated Optics and Photonic Integrated Circuits}, editor = {Righini, Giancarlo C. and Honkanen, Seppo}, publisher = {SPIE}, doi = {10.1117/12.544610}, pages = {1}, abstract = {We present first experimental results of the successful transfer of our monolithic integrated double-stack multi quantum well laser-modulator approach from the traditional InGaAsP/InP to the more promising InGaAlAs/InP material system. In continuous wave operation at room temperature, the devices achieved threshold currents of <21 mA, fiber coupled optical power levels up to 570 μW and static extinction ratios in the range of 15 dB/V. The measured small-signal modulation bandwidth of about 10 GHz is capacitance limited due to a conservative device layout.}, language = {en} } @inproceedings{SchreinerGrabeldingerWiedmannetal., author = {Schreiner, Rupert and Grabeldinger, H. and Wiedmann, J. and Wunstel, K. and Porsche, J. and Scholz, Ferdinand and Schweizer, H.}, title = {Complex coupled 1.55 mu m tunable super-grating DFB lasers and photonic filters}, series = {Compound semiconductors 1999 : proceedings of the Twenty-Sixth International Symposium on Compound Semiconductors held in Berlin, Germany, 22 - 26 August 1999}, booktitle = {Compound semiconductors 1999 : proceedings of the Twenty-Sixth International Symposium on Compound Semiconductors held in Berlin, Germany, 22 - 26 August 1999}, publisher = {Inst. of Physics Publ.}, address = {Bristol [u.a.]}, isbn = {0-7503-0704-8}, abstract = {We report on the investigation and realization of photonic filters based on the combination of fractional compositions of a few basic grating periods. Using a minimum set of two basic periods Lambda(1) and Lambda(2) we demonstrate comb-like few mode photonic band gap structures with arbitrary numbers of bands and frequency spacing between the bands. Optically integrated filters of different comb periods result in switchable wavelength filters for channel selection in WDM applications.}, language = {en} } @inproceedings{SchreinerSchweizer, author = {Schreiner, Rupert and Schweizer, Heinz C.}, title = {High frequency operation of 1.57 μm laterally gain coupled DFB lasers with self aligned ohmic contacts and nickel surface gratings}, series = {IEEE 18th International Semiconductor Laser Conference; 29 Sept.-3 Oct. 2002, Garmisch, Germany}, booktitle = {IEEE 18th International Semiconductor Laser Conference; 29 Sept.-3 Oct. 2002, Garmisch, Germany}, publisher = {IEEE}, isbn = {0-7803-7598-X}, doi = {10.1109/ISLC.2002.1041099}, pages = {21 -- 22}, abstract = {Laterally coupled DFB lasers with self-aligned ohmic contacts show the advantage of a, considerably simplified fabrication process. Side-mode-suppresion-ratios up to 55 dB and 3 dB-bandwidths beyond 15 GHz were obtained for these devices.}, language = {en} } @unpublished{MuellerWeiglMuellerWilliamsetal., author = {M{\"u}ller, Max and Weigl, Stefan and M{\"u}ller-Williams, Jennifer and Lindauer, Matthias and R{\"u}ck, Thomas and Jobst, Simon and Bierl, Rudolf and Matysik, Frank-Michael}, title = {Ambient methane monitoring at Hohenpeißenberg utilizing photoacoustic spectroscopy and cavity ring down spectroscopy}, doi = {10.5194/egusphere-2023-1010}, abstract = {With an atmospheric concentration of approximately 2000 parts per billion (ppbV, 10-9) methane (CH4) is the second most abundant greenhouse gas (GHG) in the atmosphere after carbon dioxide (CO2). The task of long-term and spatially resolved GHG monitoring to verify whether climate policy actions are effective, is becoming more crucial as climate change progresses. In this paper we report the CH4 concentration readings of our photoacoustic (PA) sensor over a five day period at Hohenpeißenberg, Germany. As a reference device a calibrated cavity ringdown spectrometer Picarro G2301 from the meteorological observatory was employed. Trace gas measurements with photoacoustic instruments promise to provide low detection limits at comparably low costs. However, PA devices are often susceptible to cross-sensitivities related to environmental influences. The obtained results show that relaxation effects due to fluctuating environmental conditions, e.g. ambient humidity, are a non-negligible factor in PA sensor systems. Applying algorithm compensation techniques, which are capable of calculating the influence of relaxational effects on the photoacoustic signal, increase the accuracy of the photoacoustic sensor significantly. With an average relative deviation of 1.11 \% from the G2301, the photoacoustic sensor shows good agreement with the reference instrument.}, language = {en} } @article{DenkSchuengelWeberetal., author = {Denk, Alexander and Sch{\"u}ngel, Verena and Weber, Stefka and Kaulen, Corinna}, title = {Heimexperiment und Online-Dokumentation : Praktische Ausbildung in den MINT-F{\"a}chern}, series = {Chemie in unserer Zeit}, journal = {Chemie in unserer Zeit}, publisher = {Wiley-VCH}, doi = {10.1002/ciuz.202100018}, abstract = {Die Anleitung zum selbst{\"a}ndigen wissenschaftlichen Arbeiten ist ein fester Bestandteil in der naturwissenschaftlichen Ausbildung, der im letzten Jahr durch Distanz-Unterricht stark vernachl{\"a}ssigt wurde. Wir stellen hier einen Ansatz vor, bei dem Studierende zu Hause mit Alltagsgegenst{\"a}nden in Teilaufgaben die Aktivit{\"a}t von Hefe in Abh{\"a}ngigkeit von Temperatur und Substrat untersucht haben. Die Ergebnisse des gesamten Kurses wurden in einem Google-Dokument gesammelt und zentral ausgewertet. Gleichzeitig fand ein Erfahrungsaustausch unter den Lernenden statt und Probleme konnten {\"o}ffentlich diskutiert werden. Dar{\"u}ber hinaus wurden grundlegende F{\"a}higkeiten wie Beobachten, Protokollieren und detailgetreues Berichten ge{\"u}bt. Die Online-Dokumentation und -Erfassung der Ergebnisse stellt somit eine geeignete Methode dar, die Durchf{\"u}hrung von Heimexperimenten zu aktivieren und zu koordinieren.}, language = {de} } @article{PourshahidiJeanKaulenetal., author = {Pourshahidi, Ali Mohammad and Jean, Neha and Kaulen, Corinna and Jakobi, Simon and Krause, Hans-Joachim}, title = {Impact of Particle Size on the Nonlinear Magnetic Response of Iron Oxide Nanoparticles during Frequency Mixing Magnetic Detection}, series = {Sensors}, volume = {24}, journal = {Sensors}, number = {13}, publisher = {MDPI}, address = {Basel}, issn = {1424-8220}, doi = {10.3390/s24134223}, abstract = {Magnetic nanoparticles (MNPs), particularly iron oxide nanoparticles (IONPs), play a pivotal role in biomedical applications ranging from magnetic resonance imaging (MRI) enhancement and cancer hyperthermia treatments to biosensing. This study focuses on the synthesis, characterization, and application of IONPs with two different size distributions for frequency mixing magnetic detection (FMMD), a technique that leverages the nonlinear magnetization properties of MNPs for sensitive biosensing. IONPs are synthesized through thermal decomposition and subsequent growth steps. Our findings highlight the critical influence of IONP size on the FMMD signal, demonstrating that larger particles contribute dominantly to the FMMD signal. This research advances our understanding of IONP behavior, underscoring the importance of size in their application in advanced diagnostic tools.}, language = {en} } @unpublished{SchwarzPastoetterTranetal., author = {Schwarz, Tobias and Past{\"o}tter, Angelina and Tran, Trung and Schlosser, Marc and Kaulen, Corinna and Lechner, Alfred and Kammler, Martin and Slabon, Adam}, title = {Effect of Temperature on the Growth of Cu(I)O Nanocubes: The Impact of the Copper Precursor Species}, series = {SSRN}, journal = {SSRN}, publisher = {Elsevier}, doi = {10.2139/ssrn.4909639}, abstract = {Cuprous oxide (Cu2O) nanoparticles were synthesized using a wet chemical surfactant free method at different synthesis temperatures from 25 ◦C to 60 ◦C. Morphology, size, and chemical composition of the prepared Cu2O nanoparticles were analyzed by SEM, PXRD, and ATR-IR. We discovered that the chemical composition of the Cu2O nanoparticles remained unaffected by the synthesis temperature. However, morphology and size of the nanoparticles showed a strong temperature dependency. This could be attributed to the temperature induced formation of cupric oxide (CuO) species from the copper hydroxide (Cu(OH)2 ) precursor which also functions as copper precursor for the Cu2O nanoparticle growth. The cupric oxide species was determined to be the main cause for the formation of micrometer sized particles, whereas with the Cu(OH)2 precursor species for the Cu2O nanoparticles nanocubes with smaller edge lengths as well as octahedrons were obtained.}, language = {en} } @unpublished{Steffens, author = {Steffens, Oliver}, title = {Binomial Distribution Nomogram after Larson}, abstract = {Following an idea of Larson (1966) we construct a nomogram for cumulative binomial distribution that can be used to perform hypothesis testing, quality management (e.g. test design) and other statistical tasks. The nomogram can be printed and directly used with a simple ruler to read the results. It is instructive and as an analog computing device continuous changes are easily visible.}, language = {en} } @incollection{HoellerBloedt, author = {H{\"o}ller, Christoph and Bl{\"o}dt, Adrian}, title = {Praxisnahe, projektbasierte Lehre in der Bauakustik mit Hilfe von realen Bauobjekten}, series = {Tagungsband - Proceedings "Fortschritte der Akustik - DAGA 2024" : DAGA 2024 - 50. Jahrestagung f{\"u}r Akustik, 18.-21. M{\"a}rz 2024, Hannover}, booktitle = {Tagungsband - Proceedings "Fortschritte der Akustik - DAGA 2024" : DAGA 2024 - 50. Jahrestagung f{\"u}r Akustik, 18.-21. M{\"a}rz 2024, Hannover}, editor = {Rolfes, Raimund and Peissig, J{\"u}rgen}, isbn = {978-3-939296-22-5}, pages = {826 -- 828}, abstract = {Im Rahmen des Masterstudiengangs Bauingenieurwesen k{\"o}nnen Studierende der Ostbayerischen Technische Hochschule Regensburg einen Wahlpflichtkurs zu fortgeschrittener Bauphysik belegen, um ihr Wissen {\"u}ber W{\"a}rme- und Feuchteverhalten, Energieeffizienz von Geb{\"a}uden sowie Raum- und Bauakustik zu vertiefen. Im letzten Jahr wurde dieser Kurs von einer klassischen Frontalvorlesung auf eine interaktivere und praxisn{\"a}here Unterrichtsform umgestellt. Im Fokus stehen nun Gruppenarbeiten und projektbasiertes Lernen mit realen Bauprojekten. F{\"u}r den Bauakustik-Teil wurde ein k{\"u}rzlich errichtetes Mehrfamilienhaus in Holzbauweise als Beispielobjekt verwendet. Die Studierenden wurden in f{\"u}nf Gruppen eingeteilt, die sich jeweils mit einem Aspekt des akustischen Planungsprozesses befassten: Luft- und Trittschalld{\"a}mmung, Raumakustik, Fassadenschalld{\"a}mmung, Ger{\"a}usche von geb{\"a}udetechnischen Anlagen sowie Immissionsschutz. Jede Gruppenaufgabe war so konzipiert, dass sie Berechnungen und messtechnische Aspekte enthielt. Die Studierenden wurden durch ausgew{\"a}hlte Vorlesungen, Kleingruppenbetreuung und einen abschließenden "Messtag" unterst{\"u}tzt. Am Ende des Semesters pr{\"a}sentierte jede Gruppe die f{\"u}r die Projektaufgaben verwendeten Methoden und die Ergebnisse. Die ersten R{\"u}ckmeldungen der Studierenden sind positiv, das Engagement hat sp{\"u}rbar zugenommen. Der praxisorientierte Ansatz impliziert, dass die Studierenden mit realen Herausforderungen konfrontiert werden, wie beispielsweise unbekannten oder fehlerhaften Daten, anspruchsvollen Messger{\"a}ten oder komplexen Vorschriften. Sie lernen, wie sie mit diesen Herausforderungen umgehen k{\"o}nnen. In diesem Beitrag werden Einzelheiten des Projekts und die bisher gesammelten Erfahrungen vorgestellt.}, language = {de} } @inproceedings{PodstranskyHausladenZlamaletal., author = {Podstr{\´a}nsk{\´y}, J{\´a}chym and Hausladen, Matthias and Zl{\´a}mal, Jakub and Kn{\´a}pek, Alexandr and Schreiner, Rupert}, title = {Single Column Multiple Electron Beam Imaging from N-Type Silicon}, series = {37th International Vacuum Nanoelectronics Conference (IVNC), 15-19 July 2024, Brno, Czech Republic}, booktitle = {37th International Vacuum Nanoelectronics Conference (IVNC), 15-19 July 2024, Brno, Czech Republic}, publisher = {IEEE}, isbn = {979-8-3503-7976-1}, doi = {10.1109/IVNC63480.2024.10652470}, pages = {1 -- 2}, abstract = {This work is aimed at measuring the electron emission from multiple cathodes formed by n-doped silicon and imaging the electron beams focused by an einzel lens on a CMOS camera. The experimental results are compared with computer simulation to understand the electron emission from the semiconductor cathode and the observed imaging imperfections. Finally, modifications to the experimental setup are suggested that should lead to improvement in the extraction current and spot size of focused electron beams and also better understanding of the processes taking place in the experiment.}, language = {en} } @inproceedings{HoellerMuellerTrapet, author = {H{\"o}ller, Christoph and M{\"u}ller-Trapet, Markus}, title = {Measured and predicted sound transmission through a laboratory concrete floor}, series = {53rd International Congress and Exposition on Noise Control Engineering (Inter-Noise 2024), 25.-29. August 2024, Nantes France}, booktitle = {53rd International Congress and Exposition on Noise Control Engineering (Inter-Noise 2024), 25.-29. August 2024, Nantes France}, language = {en} } @inproceedings{RiegerDaeubleSchecketal., author = {Rieger, Anna and D{\"a}uble, Lukas and Scheck, Jochen and Zeitler, Berndt and H{\"o}ller, Christoph}, title = {Experimental study on using transient excitation signals in the prediction of sound pressure levels from building services according to EN 12354-5 and EN 15657}, series = {Proceedings of DAS|DAGA 2025, 51st Annual Meeting on Acoustics, March 17-20, 2025, Copenhagen}, booktitle = {Proceedings of DAS|DAGA 2025, 51st Annual Meeting on Acoustics, March 17-20, 2025, Copenhagen}, address = {Berlin}, organization = {Deutsche Gesellschaft f{\"u}r Akustik e.V. (DEGA), Berlin}, isbn = {978-3-939296-23-2}, doi = {10.71568/dasdaga2025.526}, pages = {372 -- 375}, abstract = {EN 12354-5:2023 describes a calculation procedure to predict the sound pressure levels from building service equipment. The procedure uses the blocked force of the source as input data. This quantity can be determined using the reception plate method according to EN 15657:2017. The methods have been developed and validated for stationary excitation signals (Leq). Real structure-borne sound sources often have time-varying excitation signals. In addition, the requirements for sound insulation against noise from building service equipment in Germany (DIN 4109) are given in terms of the maximum, time-weighted sound pressure level (LFmax). This contribution investigates the suitability of the methods described in EN 12354-5 and EN 15657 for structure-borne sound sources with transient excitation signals. A measurement series with time signals ranging from stationary to highly transient was conducted in a building-like laboratory. The reverberation time of the receiving room was adjusted to three different values. The calculations were processed using Leq values, LFmax values and short-time Leq values. The results show the uncertainties that can arise in the prediction of signals with varying transient characteristics compared to stationary excitation signals.}, language = {en} } @inproceedings{HoellerParzingerSchanda, author = {H{\"o}ller, Christoph and Parzinger, Michael and Schanda, Ulrich}, title = {The Sound Reduction Index of Homogeneous Building Elements according to Annex B of ISO 12354-1 - Discussion and Proposal for Changes}, series = {Proceedings of DAS|DAGA 2025, 51st Annual Meeting on Acoustics, March 17-20, 2025, Copenhagen}, booktitle = {Proceedings of DAS|DAGA 2025, 51st Annual Meeting on Acoustics, March 17-20, 2025, Copenhagen}, address = {Berlin}, organization = {Deutsche Gesellschaft f{\"u}r Akustik e.V. (DEGA), Berlin}, isbn = {978-3-939296-23-2}, doi = {10.71568/dasdaga2025.147}, pages = {312 -- 315}, abstract = {Annex B of ISO 12354-1:2017 describes a procedure for the calculation of the frequency-dependent sound reduction index of homogeneous building elements such as concrete floors or masonry walls. With the introduction of EN 12354-5:2023 and an upcoming change in DIN 4109-2 regarding the calculation of sound levels due to service equipment, it is anticipated that the practical relevance and usage of Annex B will increase in the future. For this reason, the procedure has recently been investigated by an informal working group of academics from several German universities. It was found that Annex B contains some errors, missing references, and ambiguities in the calculation procedure. Based on these discussions, some changes were proposed to the committee responsible for the standard (CEN/TC 126/WG 2). While the general calculation procedure was left unchanged, the proposed changes focus on the influence of shear deformation, the radiation factor for free waves, a moving average function to limit the variability in the coincidence region, and the calculation examples provided in the annex. This contribution provides an overview of the procedure, presents some background information on the underlying theory, and discusses the proposed changes.}, language = {en} } @inproceedings{BaeumlerHoeller, author = {B{\"a}umler, Georg and H{\"o}ller, Christoph}, title = {Modifying a Wall Transmission Suite to Measure Diffuse Field Sound Absorption Coefficients - A Case Study}, series = {Proceedings of DAS|DAGA 2025, 51st Annual Meeting on Acoustics, March 17-20, 2025, Copenhagen}, booktitle = {Proceedings of DAS|DAGA 2025, 51st Annual Meeting on Acoustics, March 17-20, 2025, Copenhagen}, address = {Berlin}, organization = {Deutsche Gesellschaft f{\"u}r Akustik e.V. (DEGA), Berlin}, isbn = {978-3-939296-23-2}, doi = {10.71568/dasdaga2025.291}, pages = {1191 -- 1194}, abstract = {The determination of the diffuse field sound absorption coefficient is carried out in reverberation chambers that comply with the requirements of the corresponding standard, ISO 354. No such chamber exists at OTH Regensburg University of Applied Sciences, but a new wall transmission suite according to ISO 10140 is available. This student project investigates the possibility of using the wall transmission suite to measure absorption coefficients for teaching and research purposes.To assess the suitability of the room, the diffusivity was evaluated using the standard deviation of both the reverberation times and the equivalent continuous sound pressure levels at multiple positions within the room. These results, along with a comparison with expected values for a diffuse sound field, guided the design of reflector panels to introduce diffuse reflections. The implementation features acrylic (PMMA) as the primary material in combination with dense viscoelastic damping sheets, resulting in a low vibration solution. Suspended from the ceiling of the chamber, these improved the diffusivity of the sound field, making the room suitable for absorption measurements across a broad frequency range.}, language = {en} } @techreport{BresinskyPetzke, author = {Bresinsky, Markus and Petzke, Jan}, title = {Russland 2030+}, publisher = {OTH Regensburg}, doi = {10.35096/othr/pub-7839}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-78395}, abstract = {Der Bericht "Russland 2030+: Wege in eine ungewisse Zukunft" pr{\"a}sentiert m{\"o}gliche Szenarien f{\"u}r die politische, wirtschaftliche, milit{\"a}rische und gesellschaftliche Entwicklung Russlands bis {\"u}ber das Jahr 2030 hinaus. Er basiert auf einem interdisziplin{\"a}ren Ansatz und verwendet Foresight-Methoden, darunter eine PMESII-Analyse. Diese wurde von Studierenden der OTH Regensburg unter Leitung von Prof. Dr. Markus Bresinsky in Zusammenarbeit mit Vertretern der Bundeswehr durchgef{\"u}hrt. Der Bericht stellt f{\"u}nf Zukuntsbilder vor, die sich jeweils auf unterschiedliche Schl{\"u}sselfaktoren und Annahmen st{\"u}tzen: von einer Fortf{\"u}hrung der autorit{\"a}ren Herrschaft (Putin's Tsardom) {\"u}ber gewaltsame Machtwechsel (Moscow Meltdown) bis hin zur zunehmenden Abh{\"a}ngigkeit von China (Dragon eats Bear). Ziel der Untersuchung ist es, m{\"o}gliche Entwicklungen und deren Implikationen f{\"u}r internationale Akteure aufzuzeigen, um eine fundierte Entscheidungsgrundlage f{\"u}r vorausschauendes Handeln zu schaffen.}, language = {de} } @inproceedings{NeugartBresinsky, author = {Neugart, Sandrine and Bresinsky, Markus}, title = {Situational Awareness of Critical Infrastructures at the Local Level - Fostering Resilience Through Accessible Method-based Analysis}, series = {Critical Infrastructure Protection and Resilience Europe (CIPRE) 2022, Bukarest (Rum{\"a}nien)}, booktitle = {Critical Infrastructure Protection and Resilience Europe (CIPRE) 2022, Bukarest (Rum{\"a}nien)}, doi = {10.35096/othr/pub-5567}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-55676}, pages = {IV, 14, XI}, abstract = {Critical infrastructure protection and resilience start at the local level. While laws and regulations provide the necessary frameworks within which the various stakeholders act, little effort has been made to bring together local and regional actors in order to facilitate a shared understanding of critical infrastructure (CI) risks and security. Such a common analysis, however, is essential to identifying local vulnerabilities, understanding their key drivers as well as their interdependencies, and ultimately, to adapting strategies which overall contribute to improving the security of KRITIS in the region. This paper outlines a best practice approach to analyzing risks associated with KRITIS and their interdependencies at the local level. It addresses frequently overlooked issues such as bringing together different stakeholders whilst making the discussion accessible and comprehensible to everyone. It also deals with analytic questions regarding the development of a methods-based approach to situational awareness, ranging from defining appropriate categories of thinking to mitigating the impact of potential biases influencing the different thought processes. In order to advance these ideas, the analysis is based on thorough research as well as first-hand experience from running local workshops for stakeholders of KRITIS. Overall, this paper seeks to develop a format which encourages action among KRITIS stakeholders at the local level. It approaches critical infrastructures from a system thinking perspective, whilst linking intellectual accessibility with the rigor of academic analysis.}, language = {en} } @misc{BresinskyHagerXanthos, author = {Bresinsky, Markus and Hager, Eva and Xanthos, George}, title = {ChatGPT for futures: how large language models can support the development of future scenarios using the Cone of Plausibility}, series = {CCEW SYMPOSIUM 2024: Predictive Synergies: Crisis Early Warning \& Foresight, 19. und 20. September 2024, M{\"u}nchen}, journal = {CCEW SYMPOSIUM 2024: Predictive Synergies: Crisis Early Warning \& Foresight, 19. und 20. September 2024, M{\"u}nchen}, doi = {10.35096/othr/pub-7781}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-77811}, abstract = {Recently, large language models (LLMs), such as the "Chat Generative Pre-trained Transformer", commonly known as ChatGPT, are substantially impacting the world of (big) data analytics and artificial intelligence. This paper explores how ChatGPT-4 can be used to support the development of future scenarios using the Cone of Plausibility method. The most recent version ChatGPT 4.0 differs from its predecessors in that it can now access real-time data to generate its responses. This makes it an attractive tool for intelligence analysts, who are faced with the permanent challenge of having to sift through large amounts of data whilst also providing actionable products in a timely manner. Previous versions of ChatGPT were prone to errors such as making up information. But what if, using the right prompts, version 4.0 could become a useful sparring partner for developing future scenarios? In this study, we will ask ChatGPT 4.0 to generate sets of plausible future scenarios for "Russia 2035+" based on previously specified key drivers and assumptions. The LLM's potential for error is reduced because it is not working with hypotheses that it has generated itself. This could turn ChatGPT into a quick-thinking sparring partner for imagining varieties of future scenarios, supporting out-of-the box thinking and further minimising cognitive biases. To evaluate the reliability and accuracy of the results generated by ChatGPT, we will use the VV\&A concept developed by the US Department of Defence. According to this concept, credibility in an intelligence product is rooted in the verification, validation and accreditation of its analysis. This process is routinely followed by every intelligence analyst. We will have found out to which extent and under which circumstances ChatGPT 4.0 can credibly support the development of future scenarios.}, language = {en} } @inproceedings{ReusnerPoehnerBresinsky, author = {Reusner, Florian and P{\"o}hner, Miriam and Bresinsky, Markus}, title = {The Joint Effort Workshop as a tool for Knowledge Management and competence development}, series = {5th International Conference on Higher Education Advances (HEAd'19): 26.06.2019 - 28.06.2019, Valencia}, booktitle = {5th International Conference on Higher Education Advances (HEAd'19): 26.06.2019 - 28.06.2019, Valencia}, publisher = {Universitat Polit{\`e}cnica Val{\`e}ncia}, address = {Valencia}, isbn = {9788490486610}, doi = {10.4995/head19.2019.9305}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-26973}, abstract = {Cybersecurity is a complex global phenomenon where the risk for individuals, organisation and the society at large are at risk. These risks need to be in focus and solutions for the prevention and developing countermeasures. In this paper, we describe the Joint Effort Workshop as an approach to raise awareness to these threads and the possibility to generate and exchange knowledge between students and experts. We conclude that mechanisms for systematic response to attacks need the developed technical requirements, but foremost human behaviour, knowledge and resilience to response to risks, which can be experienced through the collaborative environment of the Joint Effort Workshop}, language = {en} } @misc{Bresinsky, author = {Bresinsky, Markus}, title = {Strategic Forecasting with Machine Learning for Geopolitical Analysis}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-25103}, language = {en} } @inproceedings{BresinskySchroederViscardi, author = {Bresinsky, Markus and Schroeder, Johanna and Viscardi, Valerio}, title = {Asymmetry in Trust Building - different perspectives in gains and losses explained via Prospect Theory}, series = {Common Effort Conference, The Hague: 19 - 22 October 2020}, booktitle = {Common Effort Conference, The Hague: 19 - 22 October 2020}, organization = {Common Effort Community}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-24778}, pages = {1 -- 9}, abstract = {Building trust within conflicts situations is a required process to establish a suitable environment for peace keeping and state building processes. However, it remains unclear what are the best ways to foster trusts between actors in a conflict environment. This study draws insights from the literature on trust and from Kahneman's Prospect Theory to analyse the decision-making dynamics of the actors involved in a conflict and how these dynamics could affect the trust levels between those actors. To this purpose, the fourfold pattern of preferences I applied to a thought experiments where opposing actors in a conflict in the Sahel face the decision to accept or refuse a peace agreement when either one of the two actors face huge gains or catastrophic losses. The main findings is that, in those extreme situations, the actors involved tend to take unnational decisions that undermine the trust building process in the country. Therefore, it would be recommendable to boost situations where actors are negotiating in a more balanced environment. To this purpose, further research should be conducted on the ways to create such suitable environment for trust building.}, language = {en} } @inproceedings{BresinskySchroederViscardi, author = {Bresinsky, Markus and Schroeder, Johanna and Viscardi, Valerio}, title = {Strategic Forecasting with Machine Learning for Regional Geopolitical Analysis}, series = {Η Περιφερειακή Επιστήμη, το μέλλον της και οι προκλήσεις στα πεδία της έρευνας και της εφαρμογής : 21ο Επιστημονικό Συνέδριο του Συνδέσμου Ελλήνων Περιφερειολόγων Ελληνικό Μεσογειακό Πανεπιστήμιο, Ηράκλειο Κρήτης, 16-17 Οκτωβρίου 2020 - Challenges for the Future of Regional Science: Research and Applications; 21st Conference: Heraklion, Crete, Oktober 2020}, booktitle = {Η Περιφερειακή Επιστήμη, το μέλλον της και οι προκλήσεις στα πεδία της έρευνας και της εφαρμογής : 21ο Επιστημονικό Συνέδριο του Συνδέσμου Ελλήνων Περιφερειολόγων Ελληνικό Μεσογειακό Πανεπιστήμιο, Ηράκλειο Κρήτης, 16-17 Οκτωβρίου 2020 - Challenges for the Future of Regional Science: Research and Applications; 21st Conference: Heraklion, Crete, Oktober 2020}, isbn = {978-618-00-2351-0}, pages = {267 -- 276}, abstract = {Strategic forecasting of regional geopolitical development is important for early warning and contingency planning. Open source data and machine learning can help to identify indicators for effective scenario development. Using data of the Bertelsmann Transformation Index (BTI) and the machine learning software Waikato Environment for Knowledge Analysis (WEKA), this paper gives an insight into the generation of a decision tree to provide indicators for forecasting regional development across parts of Northern and Western Africa. Results show that machine learning with open source data can support redefining indicator development but does not replace critical thinking.}, language = {mul} } @article{Bresinsky, author = {Bresinsky, Markus}, title = {Understanding Hybrid Warfare as Asymmetric Conflict : Systemic Analysis by Safety, Security and Certainty}, series = {On-line Journal Modelling the New Europe}, journal = {On-line Journal Modelling the New Europe}, number = {21}, publisher = {Babes-Bolyai University}, pages = {29 -- 51}, abstract = {The emergence of innovative methods and operations in asymmetric conflicts as for example unidentifiable soldiers during the Crimean conflict in 2014 or sophisticated cyberattack against Estonia in 2007 was a trigger for both analysts and scholars to rethink scientific concepts of asymmetric conflict. With introduction of the concept 'hybrid warfare' a new systematic element was established in scientific research. Nevertheless, the concept is discussed rather controversially and often its scientific value is questioned. Most of the literature describes the empirical phenomena of hybrid warfare, but does not provide a theoretical based argumentation. This paper addresses the neglected aspect of systemic analysis by focusing on vulnerability of modern societies and outlines a concept based on the theoretical idea of safety, security and certainty to grasp the underlying driving factors of new forms and methods in asymmetric conflicts. The analysis presented here shows that sociology and system engineering have already developed valuable conceptual definitions of safety, security and certainty that can be used for the analysis of asymmetric conflicts. The missing link, closed by this paper, was an interdisciplinary approach to integrate these concepts into an analysis framework. The findings indicated that the new forms of asymmetric conflicts can be understood as a concise and precise analysis of systemic weaknesses of nation states and their societies. Still, Western European nations focus their security policy mainly on past challenges of war and peace. Therefore, societies of these nations remain highly vulnerable to safety threats and uncertainty. The presented theoretical framework supported this result and should, therefore, be of value to analysts and scientists alike aiming to identify the underlying systemic factors of innovative asymmetric conflict.}, language = {en} } @inproceedings{BresinskyWillner, author = {Bresinsky, Markus and Willner, Sophia}, title = {GLOBE - Digital Literacy and Organizational Learning by Scenario-Driven Exercises}, series = {Interactivity, Game Creation, Design, Learning, and Innovation: 8th EAI International Conference, ArtsIT 2019, and 4th EAI International Conference, DLI 2019: Aalborg, Denmark, November 6-8, 2019, Proceedings}, booktitle = {Interactivity, Game Creation, Design, Learning, and Innovation: 8th EAI International Conference, ArtsIT 2019, and 4th EAI International Conference, DLI 2019: Aalborg, Denmark, November 6-8, 2019, Proceedings}, editor = {Brooks, Anthony L. and Brooks, Eva Irene}, publisher = {Springer International Publishing}, address = {Cham}, isbn = {978-3-030-53293-2}, doi = {10.1007/978-3-030-53294-9_51}, pages = {671 -- 682}, abstract = {Due to rapid technological development and fast-changing working environments, organizations active in such context find themselves facing internal change and adaption processes. Originally prominent among start-up or IT-companies, the use of management concepts to steer such change processes and to increase efficiency also spread among humanitarian organizations preoccupied with crisis management. In this regard, concepts retrieved from the domain of Organization Development offer a great potential to facilitate change processes and to enhance learning among practitioners. The notions of Learning Organization and Quality Management are combined with the theory of Argyris and Sch{\"o}n's Levels of Learning. This combination then serves as a theoretical decision-making base used in a simulation game at the University of Applied Sciences OTH Regensburg. Within this scenario-driven exercise, Quality Management, virtual collaboration and digital skills are trained. During the simulation game, participants are encouraged to think critically, to utilize new technologies and to apply their problem-solving skills to real-life examples, which ultimately aims at preparing students for a dynamic working environment within the era of digitization.}, language = {en} } @inproceedings{BresinskyWillner, author = {Bresinsky, Markus and Willner, Sophia}, title = {GLOBE - Cognitive and Social Competence Development by Virtual Collaboration and Simulation Games}, series = {Interactivity, Game Creation, Design, Learning, and Innovation. 8th EAI International Conference, ArtsIT 2019, and 4th EAI International Conference, DLI 2019, Aalborg, Denmark, November 6-8, 2019, Proceedings}, booktitle = {Interactivity, Game Creation, Design, Learning, and Innovation. 8th EAI International Conference, ArtsIT 2019, and 4th EAI International Conference, DLI 2019, Aalborg, Denmark, November 6-8, 2019, Proceedings}, editor = {Brooks, Anthony L. and Brooks, Eva Irene}, publisher = {Springer International Publishing}, address = {Cham}, isbn = {978-3-030-06133-3}, doi = {10.1007/978-3-030-06134-0_37}, pages = {331 -- 342}, abstract = {This paper first examines a variety of conceptual contemporary challenges and cognitive shortcomings of public policy makers, entrepreneurs and other practitioners in Germany as a knowledge-based economy. Systems thinking, digital competencies and several modern leadership skills are identified as possibilities to meet contemporary challenges in fast changing and complex environments. Modern leadership skills and promising working styles imply the ability to manage agile processes, flexibility and diversity, and the modus operandi as self-organizing networks. After that, the simulation game GLOBE Exercise at the OTH Regensburg is introduced as an innovative and transformative learning method. In its concept, the GLOBE Exercise combines virtual collaboration with Action Learning, and thus contributes to skills development and transfer both concerning digital competencies and analytical skills.}, language = {en} } @incollection{BresinskyDetjeLittschwager, author = {Bresinsky, Markus and Detje, Frank and Littschwager, Martin}, title = {Milit{\"a}r: Handeln in komplexen Problemlagen}, series = {Human Factors: Psychologie sicheren Handelns in Risikobranchen}, booktitle = {Human Factors: Psychologie sicheren Handelns in Risikobranchen}, editor = {Badke-Schaub, Petra and Hofinger, Gesine and Lauche, Kristina}, publisher = {Springer}, isbn = {978-3-642-19886-1}, doi = {10.1007/978-3-642-19886-1_15}, pages = {263 -- 274}, language = {en} } @inproceedings{BresinskyVorderwestnerSuenderhauf, author = {Bresinsky, Markus and Vorderwestner, Anna and S{\"u}nderhauf, Elena}, title = {GLOBE Tabletop - Capability Development through Pre-Exercise Learning for Humanitarian Missions}, series = {10th International Conference on Higher Education Advances (HEAd'24), June 18, 2024 - June 21, 2024, Val{\`e}ncia}, booktitle = {10th International Conference on Higher Education Advances (HEAd'24), June 18, 2024 - June 21, 2024, Val{\`e}ncia}, issn = {2603-5871}, doi = {10.4995/HEAd24.2024.17180}, abstract = {Simulation exercises play a significant role in training for humanitarian missions and provide suitable space for appropriate preparation of humanitarian personnel. It was observed that participants in the GLOBE simulation, a humanitarian crisis simulation exercise, lacked fundamental knowledge concerning structure and process organization, situational awareness, and complex planning tasks. Thus, this paper explores the concept of capability development through pre-exercise learning, suggests improvements of the efficacy and effectiveness of learning for individuals engaged in humanitarian mission simulations, and provides implications for improving the overall effectiveness and outcomes of simulation exercises. The conceptualization of pre-exercise learning with gamification and tabletop exercise elements prior to participation in the simulation exercise is expected to lead to enhanced capability development during the simulation of humanitarian missions.}, language = {en} } @incollection{BresinskyStrat, author = {Bresinsky, Markus and Strat, Francesca Elena}, title = {ChatGPT supporting intelligence analysis in strategic forecasting}, series = {Zagrożenia i wyzwania bezpieczeństwa w cyberprzestrzeni}, booktitle = {Zagrożenia i wyzwania bezpieczeństwa w cyberprzestrzeni}, editor = {Pomykala, Marta and Oleksiewicz, Izabela}, publisher = {Oficyna Wydawnicza Politechniki Rzeszowskiej}, address = {Rzesz{\´o}w}, pages = {231 -- 258}, language = {en} } @article{SchmidtDenkerDashielletal., author = {Schmidt, Oliver G. and Denker, Ullrich and Dashiell, Michael W. and Jin-Phillipp, Neng Yun and Eberl, Karl and Schreiner, Rupert and Gr{\"a}beldinger, Hedwig and Schweizer, Heinz C. and Christiansen, Silke H. and Ernst, Frank}, title = {Laterally aligned Ge/Si islands: a new concept for faster field-effect transistors}, series = {Materials Science and Engineering B}, volume = {89}, journal = {Materials Science and Engineering B}, number = {1-3}, publisher = {Elsevier}, address = {New York, NY}, issn = {1873-4944}, doi = {10.1016/S0921-5107(01)00810-8}, pages = {101 -- 105}, abstract = {Self-assembled and coherently strained Ge dots were grown on a Si/SiGe superlattice, which was deposited on a flat Si(001) substrate surface patterned with a regular array of straight trenches. The superlattice translates the surface modulation of the substrate into a strain-field modulation, which causes the Ge dots on its surface to form along straight lines above the buried trenches. This approach provides self-assembled Ge dots with excellent lateral periodicity, which might be useful for fabricating dot-based field-effect-transistors (DotFETs). Here, we propose the concept of a modulation-doped p-channel DotFET (p-MOD-DotFET). The p-MOD-DotFET relies on embedded Ge-rich nanostructures, which provide p-channels through the Ge-rich dots. A high Ge concentration in the dots is desirable in order to exploit the high hole mobility of Ge-rich material. We show that the commonly observed Si-Ge intermixing during Si capping of Ge dots can be suppressed by overgrowing the islands at low temperature.}, language = {en} } @article{RueckMuellerJobstetal., author = {R{\"u}ck, Thomas and M{\"u}ller, Max and Jobst, Simon and Weigl, Stefan and Pangerl, Jonas and Bierl, Rudolf and Matysik, Frank-Michael}, title = {Digital Twin of a Photoacoustic Trace Gas Sensor for Monitoring Methane in Complex Gas Compositions}, series = {Sensors and Actuators B: Chemical}, journal = {Sensors and Actuators B: Chemical}, number = {378}, doi = {10.1016/j.snb.2022.133119}, abstract = {The digitalization of industrial processes requires smart sensor systems. Photoacoustic spectroscopy is well suited for this purpose as it allows for small-sized and low-cost trace gas analysis. However, the method is susceptible to changes in measurement conditions and standard calibration routines often fail to correct for all changes. We therefore created a Digital Twin (DT) of a photoacoustic trace gas sensor for methane and evaluated it regarding variations in gas composition (CH4, N2, O2, CO2, H2O), temperature and pressure. With a mean absolute percentage error of 0.8 \% the accuracy of the sensor after DT compensation significantly exceeds the 24 \% achieved based on standard calibration in nitrogen. For the first time, we can fully analytically compute the photoacoustic signal under moderate ambient conditions with an error in the ppbV range by taking a holistic approach. Assuming knowledge of the underlying energy transfer processes, the model of this Digital Twin can be adapted to any microphone based photoacoustic sensor for monitoring any analyte species.}, language = {en} } @inproceedings{RiegerHoeller, author = {Rieger, Anna and H{\"o}ller, Christoph}, title = {Aufbau eines Empfangsplattenpr{\"u}fstands an der OTH Regensburg}, series = {Fortschritte der Akustik - DAGA 2023, 49. Jahrestagung f{\"u}r Akustik, 06. - 09. M{\"a}rz 2023, Hamburg}, booktitle = {Fortschritte der Akustik - DAGA 2023, 49. Jahrestagung f{\"u}r Akustik, 06. - 09. M{\"a}rz 2023, Hamburg}, publisher = {Deutsche Gesellschaft f{\"u}r Akustik e.V. (DEGA)}, address = {Berlin}, pages = {274 -- 277}, language = {de} } @inproceedings{EilerHoeglLindneretal., author = {Eiler, Julian and H{\"o}gl, Christina and Lindner, Matthias and Bachmann, Michael and Schreiner, Rupert}, title = {Miniaturized Surface Dielectric Barrier Discharge Plasma Actuators for Application in Chemical Analysis Systems}, series = {2023 IEEE 36th International Vacuum Nanoelectronics Conference (IVNC), 10-13 July 2023, Cambridge, MA, USA}, booktitle = {2023 IEEE 36th International Vacuum Nanoelectronics Conference (IVNC), 10-13 July 2023, Cambridge, MA, USA}, publisher = {IEEE}, isbn = {979-8-3503-0143-4}, doi = {10.1109/IVNC57695.2023.10188884}, pages = {40 -- 42}, abstract = {A new concept for a miniaturized planar ion source based on a surface dielectric barrier discharge (SDBD) is presented. A fabrication method based on a stamping process is described, and the plasma actuators are characterized based on their power in dependence of the applied voltage. The voltage for plasma ignition is approx. 1 kV with a maximum plasma power of 40 W/m at 3,4 kV.}, language = {en} } @article{ZifarelliCantatoreSampaoloetal., author = {Zifarelli, Andrea and Cantatore, Aldo Francesco Pio and Sampaolo, Angelo and Mueller, Max and Rueck, Thomas and Hoelzl, Christine and Rossmadl, Hubert and Patimisco, Pietro and Spagnolo, Vincenzo}, title = {Multivariate analysis and digital twin modelling: Alternative approaches to evaluate molecular relaxation in photoacoustic spectroscopy}, series = {Photoacoustics}, volume = {33}, journal = {Photoacoustics}, publisher = {Elsevier}, issn = {2213-5979}, doi = {10.1016/j.pacs.2023.100564}, abstract = {A comparative analysis of two different approaches developed to deal with molecular relaxation in photoacoustic spectroscopy is here reported. The first method employs a statistical analysis based on partial least squares regression, while the second method relies on the development of a digital twin of the photoacoustic sensor based on the theoretical modelling of the occurring relaxations. Methane detection within a gas matrix of synthetic air with variable humidity level is selected as case study. An interband cascade laser emitting at 3.345 µm is used to target methane absorption features. Two methane concentration ranges are explored targeting different absorptions, one in the order of part-per-million and one in the order of percent, while water vapor absolute concentration was varied from 0.3 \% up to 2 \%. The results achieved employing the detection techniques demonstrated the possibility to efficiently retrieve the target gas concentrations with accuracy > 95 \% even in the case of strong influence of relaxation effects.}, language = {en} } @inproceedings{PangerlWittmannWeigletal., author = {Pangerl, Jonas and Wittmann, Elisabeth and Weigl, Stefan and M{\"u}ller, Max and Bierl, Rudolf and Matysik, Frank-Michael}, title = {Using a Modulated Quantum Cascade Laser for Photoacoustic Spectra Recording of Exhaled Acetone and Main Breath Components}, series = {Optical Sensors and Sensing Congress 2022 (AIS, LACSEA, Sensors, ES)}, booktitle = {Optical Sensors and Sensing Congress 2022 (AIS, LACSEA, Sensors, ES)}, publisher = {Optica Publishing Group}, doi = {10.1364/AIS.2022.ATu3G.1}, abstract = {Photoacoustic spectra of main breath components together with acetone are presented demonstrating spectral linearity towards different concentrations and compositions. The acetone 3σ detection limit at 1209 cm-1 is 0.28 ppbV}, language = {en} } @article{SpillerDegenKronewaldetal., author = {Spiller, Ralf and Degen, Matthias and Kronewald, Elke and Guertler, Katherine}, title = {Media watchblogs as an instrument of media accountability: An international survey}, series = {Journal of Applied Journalism \& Media Studies}, volume = {5}, journal = {Journal of Applied Journalism \& Media Studies}, number = {2}, publisher = {intellect}, issn = {2049-9531}, doi = {10.1386/ajms.5.2.151_1}, pages = {151 -- 176}, abstract = {Media watchdog weblogs can play an important role in media accountability, provided that the bloggers are regularly active and have an appropriate awareness of their role in the media landscape. The following article examines the presence and influence of media watchblogs in selected nations, as well as the operators' standards and perceptions of their roles. In semi-structured qualitative interviews, operators of watchblogs in Germany, Austria, Switzerland and the United Kingdom discussed their perceptions of their role, their ethical guidelines, their financing and any conflicts of interest, and their projections for the future. The interviews reveal that most media watchbloggers do not interpret their role to be a Fifth Estate with a mandate to monitor the mass media. The watchbloggers are reluctant to accept and uphold formal ethical and quality criteria, and limitations on time and money make them unable to guarantee ongoing critical media analysis. For these reasons, media watchblogs are determined to be a weak instrument of media accountability.}, language = {en} } @inproceedings{BartlBuchnerHausladenetal., author = {Bartl, Mathias and Buchner, Philipp and Hausladen, Matthias and Asgharzadehkhorasani, Ali and Bachmann, Michael and Schreiner, Rupert}, title = {Simulations and Investigations of Silicon Nanowire Field Emitters}, series = {37th International Vacuum Nanoelectronics Conference (IVNC), 15-19 July 2024, Brno, Czech Republic}, booktitle = {37th International Vacuum Nanoelectronics Conference (IVNC), 15-19 July 2024, Brno, Czech Republic}, publisher = {IEEE}, doi = {10.1109/IVNC63480.2024.10652355}, pages = {1 -- 2}, abstract = {The emission behavior of field emission electron sources consisting of a silicon nanowire cathode, an extraction grid electrode and a planar anode was investigated based on a particle tracing simulation using FEM. The focus was on the influence of the grid geometry as well as the positioning of the grid relative to the emitters on the electron transmission. The highest transmission can be achieved with the emitter tips protruding 10 µm trough the extraction grid openings. The transmission decreases more rapidly with increasing distance between the tip and the grid the thicker the grid is.}, language = {en} } @inproceedings{HoellerBloedt, author = {H{\"o}ller, Christoph and Bl{\"o}dt, Adrian}, title = {Aufzugsch{\"a}chte in Holzbauweise - Konstruktionsprinzipien und Prognosem{\"o}glichkeiten f{\"u}r den Schallschutz}, series = {Forum Holzbau, Bauphysik \& Geb{\"a}udetechnik: 7. Internationale Fachtagung Bauphysik \& Geb{\"a}udetechnik (BGT 2024), 24./25. April 2024, Friedrichshafen, Deutschland}, booktitle = {Forum Holzbau, Bauphysik \& Geb{\"a}udetechnik: 7. Internationale Fachtagung Bauphysik \& Geb{\"a}udetechnik (BGT 2024), 24./25. April 2024, Friedrichshafen, Deutschland}, publisher = {Forum Holzbau}, address = {Biel}, language = {de} } @inproceedings{HoellerMuellerTrapet, author = {Hoeller, Christoph and Mueller-Trapet, Markus}, title = {Measured and predicted sound transmission through a laboratory concrete floor}, series = {INTER-NOISE and NOISE-CON Congress and Conference Proceedings, INTER-NOISE24, Nantes, France}, booktitle = {INTER-NOISE and NOISE-CON Congress and Conference Proceedings, INTER-NOISE24, Nantes, France}, publisher = {ingenta}, doi = {10.3397/IN_2024_3902}, pages = {7042 -- 7050}, abstract = {The direct sound transmission through a simple, massive, homogeneous building element with and without lining is investigated experimentally and compared with analytical and empirical models from the literature. A 150 mm thick concrete floor and a 100 mm thick floating floor were measured in the floor transmission facility of the National Research Council Canada, i.e. without flanking sound transmission. In addition to the sound reduction index and the normalized impact sound pressure level, loss factors, radiation efficiencies, and mean squared velocities were recorded in the laboratory. The measured data is compared to established models of sound transmission. A focus is placed on the calculation model of ISO 12354-1 (Appendix B), which uses calculated radiation efficiencies and loss factors to predict the sound reduction index of heavy, homogeneous building elements. Some difficulties with the calculation model and the examples in the standard are discussed. In principle, the results in this study show that the calculation model of ISO 12354-1 gives good estimates when the correct input parameters are used. However, deviations between the calculated and the measured loss factors and radiation efficiencies have large effects on the accuracy of the estimates, particularly in the region around the coincidence frequency.}, language = {en} } @phdthesis{Berndt, author = {Berndt, Dominik}, title = {Thermische Wasserstoffsensoren f{\"u}r den Automobilbereich}, address = {Regensburg}, abstract = {F{\"u}r den sicheren Betrieb eines Brennstoffzellenfahrzeugs sind Sensoren wichtig, welche die Wasserstoffkonzentration im Fahrzeuginterieur kontinuierlich {\"u}berwachen, um m{\"o}glichen Entz{\"u}ndungen bzw. Explosionen vorzubeugen. Daf{\"u}r wurden von verschiedenen nationalen und internationalen Instanzen bestimmte Kriterien definiert, die Wasserstoffsensoren f{\"u}r einen Einsatz in Brennstoffzellenfahrzeugen erf{\"u}llen m{\"u}ssen. Im Jahr 2020gab es noch keinen einzigen kommerziell erh{\"a}ltlichen Sensor, der alle diese Kriterien bedienen konnte. In der vorliegenden Arbeit wurde f{\"u}r zwei verschiedene Sensoren die Eignung des thermischen Wirkprinzips f{\"u}r die Detektion von Wasserstoff im Kontext dieser Sicherheitskriterien untersucht. Dabei wurden mit einem MEMS-Sensor und einem Mikrodrahtsensor zwei vergleichsweise einfache Geometrien herangezogen, welche den eindimensionalen und zylindersymmetrischen Fall abbilden sollen. F{\"u}r zwei dynamische Operationsmodi (gepulste Str{\"o}me und 3ω-Methode) wurden darauf aufbauend analytische Modelle basierend auf vereinfachten Sensorgeometrien entwickelt, um die Temperaturentwicklung des Sensorelements in Abh{\"a}ngigkeit der Zeit zu charakterisieren. Diese Studien wurden anschließend anhand von detaillierteren Modellen mithilfe von FEM-Simulationen erg{\"a}nzt und spezifiziert. Darin konnte gezeigt werden, dass f{\"u}r den gepulsten Betrieb sowohl die Pulsh{\"o}he als auch die Zeitkonstante des gemessenen Widerstands- bzw. Temperaturpulses als Messgr{\"o}ße herangezogen werden kann. Beim 3ω-Betrieb konnte zudem eine starke Frequenzabh{\"a}ngigkeit dieser Widerstands- bzw. Temperaturcharakteristik beobachtet werden. Die analytischen und numerischen Studien wurden anschließend durch experimentelle Ergebnisse best{\"a}tigt. Im Hinblick auf die zuvor definierten Kriterien stellte sich heraus, dass die Auswertung der Zeitkonstante beim gepulsten Betrieb im Hinblick auf Sensitivit{\"a}t und Aufl{\"o}sungsgrenze der Auswertung der Pulsh{\"o}he deutlich unterlegen ist. Beim 3ω-Betrieb k{\"o}nnen durch die hochintegrierte Messumgebung deutlich h{\"o}here Genauigkeiten und Aufl{\"o}sungsgrenzen erzielt werden. F{\"u}r den MEMS-Sensor wurde bei einer Anregungsfrequenz von 1 Hz mit 55 ppm die bislang geringste in der Literatur berichtete Aufl{\"o}sungsgrenze f{\"u}r einen thermischen Wasserstoffsensor erreicht. Der Leistungsverbrauch ist dabei im Vergleich zum Pulsbetrieb entsprechend des jeweiligen Tastgrads leicht bis m{\"a}ßig erh{\"o}ht, die Ansprechzeit wird bei beiden Operationsmodi maßgeblich durch die Sensorgeometrie beeinflusst. Die geometrischen Parameter der jeweiligen Sensoren haben ferner einen starken Einfluss auf die Sensitivit{\"a}t, womit die Divergenz in der Performance von MEMS-Chip und Drahtsensor erkl{\"a}rt werden kann. Es besteht ferner eine starke Temperatur- und Feuchtigkeitsabh{\"a}ngigkeit des Sensorsignals, welches bei beiden Operationsmodi indirekt proportional zur W{\"a}rmeleitf{\"a}higkeit des betrachteten Gasgemischs ist. Die Abh{\"a}ngigkeit vom definierten Umgebungsdruck ist lediglich f{\"u}r die Zeitkonstante relevant, bei der Pulsh{\"o}he besteht keine Druckabh{\"a}ngigkeit. Es konnte eine grunds{\"a}tzliche Eignung des thermischen Messprinzips f{\"u}r den Einsatz eines Wasserstoffsensors im Automobilbereich festgestellt werden. F{\"u}r eine Anwendung m{\"u}ssen allerdings Referenzsensoren f{\"u}r Temperatur, Feuchtigkeit und Druck implementiert werden und eine Kalibrierung in Abh{\"a}ngigkeit dieser Gr{\"o}ßen erfolgen. Der 3ωBetrieb ist aufgrund der h{\"o}heren Genauigkeit zu bevorzugen. W{\"a}hrend der MEMSSensor im Hinblick auf Sensitivit{\"a}t, Ansprechzeit und Leistungsaufnahme gut abschneidet, liegen die Vorteile des Mikrodrahtsensors in seiner Robustheit und der vergleichsweise einfachen Realisierbarkeit}, subject = {Kraftfahrzeugtechnik}, language = {de} } @article{MennickenPeterKaulenetal., author = {Mennicken, Max and Peter, Sophia Katharina and Kaulen, Corinna and Simon, Ulrich and Karth{\"a}user, Silvia}, title = {Impact of device design on the electronic and optoelectronic properties of integrated Ru-terpyridine complexes}, series = {Beilstein journal of nanotechnology}, volume = {13}, journal = {Beilstein journal of nanotechnology}, publisher = {Beilstein-Institut zur F{\"o}rderung der Chemischen Wissenschaften}, doi = {10.3762/bjnano.13.16}, pages = {219 -- 229}, abstract = {The performance of nanoelectronic and molecular electronic devices relies strongly on the employed functional units and their addressability, which is often a matter of appropriate interfaces and device design. Here, we compare two promising designs to build solid-state electronic devices utilizing the same functional unit. Optically addressable Ru-terpyridine complexes were incorporated in supramolecular wires or employed as ligands of gold nanoparticles and contacted by nanoelectrodes. The resulting small-area nanodevices were thoroughly electrically characterized as a function of temperature and light exposure. Differences in the resulting device conductance could be attributed to the device design and the respective transport mechanism, that is, thermally activated hopping conduction in the case of Ru-terpyridine wire devices or sequential tunneling in nanoparticle-based devices. Furthermore, the conductance switching of nanoparticle-based devices upon 530 nm irradiation was attributed to plasmon-induced metal-to-ligand charge transfer in the Ru-terpyridine complexes used as switching ligands. Finally, our results reveal a superior device performance of nanoparticle-based devices compared to molecular wire devices based on Ru-terpyridine complexes as functional units.}, language = {en} } @article{HausladenBuchnerBartletal., author = {Hausladen, Matthias and Buchner, Philipp and Bartl, Mathias and Bachmann, Michael and Schreiner, Rupert}, title = {Integrated multichip field emission electron source fabricated by laser-micromachining and MEMS technology}, series = {Journal of Vacuum Science \& Technology B}, volume = {42}, journal = {Journal of Vacuum Science \& Technology B}, number = {1}, publisher = {AIP Publishing}, doi = {10.1116/6.0003233}, abstract = {In this work, high-current field emission electron source chips were fabricated using laser-micromachining and MEMS technology. The resulting chips were combined with commercially available printed circuit boards (PCBs) to obtain a multichip electron source. By controlling the separate electron sources using an external current control circuit, we were able to divide the desired total current evenly across the individual chips deployed in the PCB-carrier. In consequence, we were able to show a decreased degradation due to the reduced current load per chip. First, a single electron source chip was measured without current regulation. A steady-state emission current of 1 mA with a high stability of ±1.3\% at an extraction voltage of 250 V was observed. At this current level, a mean degradation slope of -0.7 μA/min with a nearly perfect transmission ratio of 99\% ± 0.4\% was determined. The measurements of a fully assembled multichip PCB-carrier electron source, using a current control circuit for regulation, showed that an even distribution of the desired total current led to a decreased degradation. This was determined by the increase in the required extraction voltage over time. For this purpose, two current levels were applied to the electron source chips of the PCB-carrier using an external current control circuit. First, 300 μA total current was evenly distributed among the individual electron source chips followed by the emission of 300 μA per electron source chip. This allows the observation of the influence of a distributed and nondistributed total current, carried by the electron source chips. Thereby, we obtained an increase in the mean degradation slope from +0.011 V/min (300 μA distributed) to +0.239 V/min (300 μA per chip), which is approximately 21 times higher. Moreover, our current control circuit improved the current stability to under 0.1\% for both current levels, 300 μA distributed and 300 μA per chip.}, language = {en} } @article{RemškarJelencCzepurnyietal., author = {Remškar, Maja and Jelenc, Janez and Czepurnyi, Nikolai and Malok, Matjaž and Pirker, Luka and Schreiner, Rupert and H{\"u}ttel, Andreas K.}, title = {Modulations of the work function and morphology of a single MoS2 nanotube by charge injection}, series = {Nanoscale Advances}, journal = {Nanoscale Advances}, publisher = {Royal Society of Chemistry (RSC)}, issn = {2516-0230}, doi = {10.1039/d4na00490f}, abstract = {Both the miniaturization of transistor components and the ongoing investigation of material systems with potential for quantum information processing have significantly increased current interest of researchers in semiconducting inorganic nanotubes. Here we report on an additional outstanding aspect of these nanostructures, namely the intrinsic coupling of electronic and mechanical properties. We observe electronic and morphology changes in a single MoS2 nanotube, exposed to charge injections by means of an atomic-force-microscopy tip. An elliptic deformation of the nanotube and helical twisting of the nanotube are visible, consistent with the reverse piezoelectric effect. Work-function changes are found to be dependent on the polarity of the injected carriers. An unexpected long-term persistence of the shape deformations is observed and explained with accumulation of structural defects and the resultant strain, which could cause a memory-like charge confinement and a long lasting modulation of the work function.}, language = {en} } @inproceedings{AliAhmmedAlEmranetal., author = {Ali, Md. Wajed and Ahmmed, Tanvir and Al Emran, Md and Roy, Dipon and Refat, Kawsar Ahmed and Khan, Robiul}, title = {Driver Fatigue Detection using CWT-Extracted Features and a Deep Learning Approach (CNNLSTM)}, series = {2024 IEEE International Conference on Biomedical Engineering, Computer and Information Technology for Health (BECITHCON), 28-29 Nov. 2024, Dhaka, Bangladesh}, booktitle = {2024 IEEE International Conference on Biomedical Engineering, Computer and Information Technology for Health (BECITHCON), 28-29 Nov. 2024, Dhaka, Bangladesh}, publisher = {IEEE}, address = {Piscataway, NJ}, isbn = {979-8-3315-3435-6}, doi = {10.1109/BECITHCON64160.2024.10962632}, pages = {77 -- 82}, abstract = {Driver fatigue is a leading reason behind traffic accidents globally, resulting in significant threats to public safety and substantial economic costs. Electroencephalography (EEG) has shown to be a critical tool for identifying driver fatigue as it can record brain activity associated with sleepiness, which gives it an advantage over other physiological modalities. Although raw EEG data can provide insightful information, accurate fatigue identification requires strong feature extraction techniques because of the inherent complexity of the data. This emphasizes how urgent it is to investigate revolutionary deep-learning architectures that can successfully extract discriminative features from raw EEG data. This study provides an innovative framework for driver fatigue identification from EEG that combines continuous wavelet transform (CWT) with convolutional neural networks (CNN) and long-short term memory (LSTM). In order to gain the advantage over the drawbacks of manual feature extraction, this study generates time-frequency spectrum representations of EEG data using the CWT. Following extracting information, each channel's time-frequency images are concatenated and fed into a CNN-LSTM architecture. This combination models the temporal and spatial characteristics of the EEG data and automatically learns discriminative features for identifying drivers' normal and fatigued states. A publicly available EEG dataset with recordings from twelve subjects is used to evaluate the proposed CWT-CNN-LSTM architecture. The result shows a prominent classification accuracy of 98.34\% for both the average of each subject and combined subjects. These findings show how well the CNN-LSTM framework captures EEG patterns associated with fatigue, which may result in more reliable driver fatigue detection systems and improved traffic safety.}, language = {en} } @article{HaynackTimothyKraenkeletal., author = {Haynack, Alexander and Timothy, Jithender J. and Kr{\"a}nkel, Thomas and Gehlen, Christoph and Thiel, Charlotte}, title = {Analyse des Frost-Tausalz-Widerstands zementgebundener Baustoffe mittels 3D-Laserscanning}, series = {ce/papers: Proceedings in Civil Engineering}, volume = {6}, journal = {ce/papers: Proceedings in Civil Engineering}, number = {6}, publisher = {Ernst \& Sohn}, issn = {2509-7075}, doi = {10.1002/cepa.2951}, pages = {1189 -- 1196}, abstract = {Eine Herausforderung performancebasierter Pr{\"u}fverfahren zur Bewertung der Dauerhaftigkeit ist die Beschleunigung nat{\"u}rlicher Mechanismen. Dies ist notwendig, um innerhalb kurzer Zeit die Langzeit-Leistungsf{\"a}higkeit ermitteln zu k{\"o}nnen. Die Bestimmung der Frost-Tausalzbest{\"a}ndigkeit von Beton kann durch den CDF-Test erfolgen, welcher f{\"u}r Betone mit ausreichendem Frost-Tausalz-Widerstand sehr gut funktioniert. Bei Proben mit einer unzureichenden bzw. unbekannten Performance k{\"o}nnen erh{\"o}hte Randabwitterungen auftreten, welche durch das Abl{\"o}sen des seitlichen Abdichtbands entstehen. Der zunehmende Randeinfluss f{\"u}hrt so zu einer Verf{\"a}lschung der Ergebnisse und zu einer Untersch{\"a}tzung der tats{\"a}chlichen Performance des Bauteils. In diesem Beitrag werden M{\"o}rtel- und Betonprobek{\"o}rper mit unterschiedlichen Abwitterungsraten in Anlehnung an das CDF-Verfahren untersucht. Zus{\"a}tzlich wird die Oberfl{\"a}chensch{\"a}digung der Proben anhand einer neuartigen Messmethode mittels hochaufl{\"o}sendem 3D-Laserscanning ausgewertet. Die Ergebnisse zeigen, dass die Randeffekte mit der Laserscan-Methode umgangen und vergleichbare Ergebnisse zu den CDF-Untersuchungen erzielt werden k{\"o}nnen. Somit k{\"o}nnen Betone ohne Randeinfl{\"u}sse charakterisiert und eine pr{\"a}zise Prognose der Langzeitbest{\"a}ndigkeit getroffen werden.}, language = {de} } @article{PeterDalmerLechneretal., author = {Peter, Daniel and Dalmer, Michael and Lechner, Alfred and Gigler, Alexander M. and Stark, Robert W. and Bensch, Wolfgang}, title = {The influence of liquid media on the fracture strength of polysilicon nanostructures}, series = {Solid State Phenomena}, volume = {187}, journal = {Solid State Phenomena}, publisher = {Trans Tech Publications}, doi = {10.4028/www.scientific.net/SSP.187.127}, pages = {127 -- 130}, abstract = {The mechanical stability of nanostructures depends on the surrounding medium. Their stability was probed by lateral force microscopy in liquid media. Previously reported data on water and isopropanol showed an increase in the fracture strength for the latter. Further tests with other alcohols (ethanol, 1-butanol) also showed an increasing strength. The interface between the liquid and the surface is the decisive factor for the influence of the media. When altering the interface with a cationic surfactant or a self-assembled monolayer, an increase of the fracture force by 100 \% compared to de-ionized water could be measured.}, language = {en} } @inproceedings{EscherRueckJobstetal., author = {Escher, Lukas and R{\"u}ck, Thomas and Jobst, Simon and K{\"o}nig, Martin and Bierl, Rudolf}, title = {Design and Characterization of a Low-Cost Photoacoustic Sensor for NO2 Using Lateral Illumination and Background Suppression}, series = {Imaging and Applied Optics Congress 2022 (3D, AOA, COSI, ISA, pcAOP): 11-15 July 2022, Vancouver, British Columbia, Canada}, booktitle = {Imaging and Applied Optics Congress 2022 (3D, AOA, COSI, ISA, pcAOP): 11-15 July 2022, Vancouver, British Columbia, Canada}, publisher = {Optica Publishing Group}, isbn = {978-1-957171-09-8}, doi = {10.1364/3D.2022.JTu2A.10}, abstract = {We introduce a low-cost photoacoustic NO2 sensor based on lateral LED illumination and optical background signal compensation. The 3σ limit of detection (LOD) was identified to be 24 ppbV.}, language = {en} } @unpublished{PangerlSukulRuecketal., author = {Pangerl, Jonas and Sukul, Pritam and R{\"u}ck, Thomas and Escher, Lukas and Miekisch, Wolfram and Bierl, Rudolf and Matysik, Frank-Michael}, title = {Photoacoustic Trace-Analysis of Breath Isoprene and Acetone Via Interband- and Quantum Cascade Lasers}, publisher = {Elsevier / SSRN}, doi = {10.2139/ssrn.4834735}, abstract = {This research presents two laser-based photoacoustic approaches for analyzing exhaled breath isoprene and acetone. The integration of a PTR-ToF-MS as a reference device ensured the reliability and accuracy of the PAS systems that is based on an ICL for isoprene and a QCL for acetone detection. The calibration yielded limits of detection of 26.9 ppbV and 1.7 ppbV, respectively, and corresponding normalized noise equivalent absorption coefficients (NNEAs) of 5.0E-9 Wcm-1Hz-0.5 and 4.9E-9 Wcm-1Hz-0.5. Laboratory as well as real breath sample measurements from alveolar breath revealed a robust system performance, with only one outlier within the static isoprene measurements. However, discrepancies emerged under dynamic breath sampling conditions, emphasizing the need for further optimization. Especially by knowing the dynamic nature and endogenous origin of exhaled isoprene our findings highlight the potential of breath analysis for non-invasive physio-metabolic and pathophysiological monitoring towards point-of-care devices.}, language = {en} } @article{PangerlSukulRuecketal., author = {Pangerl, Jonas and Sukul, Pritam and R{\"u}ck, Thomas and Escher, Lukas and Miekisch, Wolfram and Bierl, Rudolf and Matysik, Frank-Michael}, title = {Photoacoustic trace-analysis of breath isoprene and acetone via interband- and Quantum Cascade Lasers}, series = {Sensors and Actuators: B. Chemical}, volume = {424}, journal = {Sensors and Actuators: B. Chemical}, publisher = {Elsevier}, doi = {10.1016/j.snb.2024.136886}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-77024}, pages = {12}, abstract = {This research presents two laser-based photoacoustic approaches for analyzing exhaled breath isoprene and acetone. The integration of a PTR-ToF-MS as a reference device ensured the reliability and accuracy of the photoacoustic systems that is based on an ICL for isoprene and a QCL for acetone detection. The calibration yielded limits of detection of 26.9 ppbV and 1.7 ppbV, respectively, and corresponding normalized noise equivalent absorption coefficients (NNEAs) of 5.0E-9 Wcm 1Hz 0.5 and 4.9E-9 Wcm 1Hz 0.5. Laboratory as well as real breath sample measurements from alveolar breath revealed a robust system performance, with only one outlier within the static isoprene measurements. However, discrepancies emerged under dynamic breath sampling conditions, emphasizing the need for further optimization. Especially by knowing the dynamic nature and endogenous origin of exhaled isoprene our findings highlight the potential of breath analysis for non-invasive physio-metabolic and pathophysiological monitoring towards point-of-care devices}, language = {en} } @inproceedings{EscherMuellerRuecketal., author = {Escher, Lukas and M{\"u}ller, Max and R{\"u}ck, Thomas and Jobst, Simon and Bierl, Rudolf}, title = {Digitaler Zwilling photoakustischer Spurengassensoren zur Prozess{\"u}berwachung}, series = {16. Dresdner Sensor-Symposium 2022: Vortr{\"a}ge}, booktitle = {16. Dresdner Sensor-Symposium 2022: Vortr{\"a}ge}, publisher = {AMA (Association for Sensors + Measurement)}, isbn = {978-3-9819376-7-1}, doi = {10.5162/16dss2022/3.3}, abstract = {Stickstoffdioxid (NO2) wird haupts{\"a}chlich durch anthropogene Verbrennungsprozesse in Verkehr und Industrie in die Umgebungsluft eingebracht [1]. Die stark reaktive, oxidative Wirkung von NO2 kann bei Exposition mit h{\"o}heren Konzentrationen Reizungen und allergische Reaktionen in den Atemwegen hervorrufen. Weiter f{\"u}hrt NO2 zur Bildung von saurem Regen, Smog und Ozon (O3) die sich ebenso negativ auf die menschliche Gesundheit und Umwelt auswirken [2,3]. Aufgrund dieser Effekte wird die Spurengaskonzentration von NO2 in der Luft in Deutschland an ausgew{\"a}hlten, verkehrsreichen Orten gemessen.}, language = {de} } @article{RueckPangerlEscheretal., author = {R{\"u}ck, Thomas and Pangerl, Jonas and Escher, Lukas and Jobst, Simon and M{\"u}ller, Max and Bierl, Rudolf and Matysik, Frank-Michael}, title = {Kinetic cooling in mid-infrared methane photoacoustic spectroscopy: A quantitative analysis via digital twin verification}, series = {Photoacoustics}, volume = {40}, journal = {Photoacoustics}, publisher = {Elsevier}, doi = {10.1016/j.pacs.2024.100652}, abstract = {This study presents a detailed quantitative analysis of kinetic cooling in methane photoacoustic spectroscopy, leveraging the capabilities of a digital twin model. Using a quantum cascade laser tuned to 1210.01 cm⁻¹, we investigated the effects of varying nitrogen-oxygen matrix compositions on the photoacoustic signals of 15 ppmV methane. Notably, the photoacoustic signal amplitude decreased with increasing oxygen concentration, even falling below the background signal at oxygen levels higher than approximately 6 \%V. This phenomenon was attributed to kinetic cooling, where thermal energy is extracted from the surrounding gas molecules rather than added, as validated by complex vector analysis using a previously published digital twin model. The model accurately reproduced complex signal patterns through simulations, providing insights into the underlying molecular mechanisms by quantifying individual collision contributions. These findings underscore the importance of digital twins in understanding the fundamentals of photoacoustic signal generation at the molecular level.}, language = {en} } @article{LeonhardtGuertler, author = {Leonhardt, Carina and Guertler, Katherine}, title = {Unearthing Corporate Greenwashing: A Content Analysis of Sustainability Reporting in the Mining Sector}, series = {Tripodos}, volume = {2025}, journal = {Tripodos}, number = {57}, publisher = {Blanquerna School of Communication and International Relations}, address = {Barcelona}, issn = {1138-3305}, doi = {10.51698/tripodos.2025.57.06}, pages = {78 -- 97}, abstract = {Greenwashing is a common form of corporate disinformation that is often challenging for the general public to detect. Companies engage in greenwashing in their reporting to mislead shareholders and stakeholders about their environmental efforts, seeking to enhance legitimacy and gain competitive advantages. While systems for identifying greenwashing exist, they typically focus on advertising, leaving greenwashing in corporate reports underexamined. This study aims to address this gap by conducting a qualitative content analysis of a climate report from a mining and commodity trading company, considering the company's profile, the report's target audience, and current research. The findings reveal that the company employs numerous subtle greenwashing strategies to project a more sustainable image through strategic omissions, hedging and vague long-term goals. Moreover, this research broadens the scope of greenwashing analysis to include corporate reporting, which targets a more informed audience, such as shareholders and experts, rather than the general public. The results underscore the need for stricter regulation of sustainability reports and highlight the importance of fostering greater scrutiny among shareholders.}, language = {en} } @incollection{MuehlbergerSchoplocherSteffens, author = {M{\"u}hlberger, Thomas and Schoplocher, Paul Dragos and Steffens, Oliver}, title = {Thermische Geb{\"a}udesimulation: aktuelle Anwendungen und Erweiterungen mittels der Finite-Elemente-Methode}, series = {Bauphysik-Kalender 2025: Simulationen, BIM und KI}, booktitle = {Bauphysik-Kalender 2025: Simulationen, BIM und KI}, editor = {Fouad, Nabil A.}, publisher = {Ernst \& Sohn}, address = {Berlin}, isbn = {9783433034514}, doi = {10.1002/9783433612095.ch12}, pages = {435 -- 468}, abstract = {Nach einem kurzen historischen Abriss der Entwicklung der Geb{\"a}udesimulation wird die aktuell {\"u}bliche gleichungsbasierte Kompaktmodell-Simulation beschrieben und deren praktische Anwendung aufgezeigt. Dabei wird auf die Bedeutung der Validierung von Simulationstools und auf etablierte Validierungsstandards eingegangen. Geb{\"a}udesimulation dient der Optimierung des Bauens in allen Planungsphasen. Mit Praxisbeispielen vom sommerlichen W{\"a}rmeschutz bis hin zur Modellierung innovativer Konstruktionen werden unterschiedliche Einsatzbereiche demonstriert. Im zweiten Teil wird die Verwendung der Finite-Elemente-Methode (FEM) f{\"u}r die bauphysikalische Modellierung vorgestellt. Anhand von Beispielen zeigen wir, dass die (rechenzeitintensive) FEM aufgrund einer detaillierteren Modellierung von Geometrie, Strahlung und Konvektion pr{\"a}zisere Simulationsergebnisse liefert. Zum Abschluss werden Wege vorgeschlagen, wie dies zur Erweiterung der schnelleren Kompaktmodell-Simulation eingesetzt werden kann.}, language = {de} } @article{JobstRecumEcijaArenasetal.2023, author = {Jobst, Simon and Recum, Patrick and {\´E}cija-Arenas, {\´A}ngela and Moser, Elisabeth and Bierl, Rudolf and Hirsch, Thomas}, title = {Semi-Selective Array for the Classification of Purines with Surface Plasmon Resonance Imaging and Deep Learning Data Analysis}, series = {ACS sensors}, volume = {8}, journal = {ACS sensors}, number = {9}, publisher = {American Chemical Society}, doi = {10.1021/acssensors.3c01114}, pages = {3530 -- 3537}, year = {2023}, abstract = {In process analytics or environmental monitoring, the real-time recording of the composition of complex samples over a long period of time presents a great challenge. Promising solutions are label-free techniques such as surface plasmon resonance (SPR) spectroscopy. They are, however, often limited due to poor reversibility of analyte binding. In this work, we introduce how SPR imaging in combination with a semi-selective functional surface and smart data analysis can identify small and chemically similar molecules. Our sensor uses individual functional spots made from different ratios of graphene oxide and reduced graphene oxide, which generate a unique signal pattern depending on the analyte due to different binding affinities. These patterns allow four purine bases to be distinguished after classification using a convolutional neural network (CNN) at concentrations as low as 50 μM. The validation and test set classification accuracies were constant across multiple measurements on multiple sensors using a standard CNN, which promises to serve as a future method for developing online sensors in complex mixtures.}, language = {en} } @inproceedings{HauslerWunderlichFischeretal., author = {Hausler, Peter and Wunderlich, Lukas and Fischer, Johannes and Pfab, Christina and Heckscher, Simon and Hirsch, Thomas and Bierl, Rudolf}, title = {Surface plasmon resonance imaging for detection of drug metabolites in water}, series = {Proceedings of SPIE, Optical Sensors 2019, 1 - 4 April 2019, Prague, Czech Republic}, volume = {Vol. 11028}, booktitle = {Proceedings of SPIE, Optical Sensors 2019, 1 - 4 April 2019, Prague, Czech Republic}, issn = {0277-786X}, doi = {10.1117/12.2522324}, pages = {11}, abstract = {The analysis of surface water, groundwater, drinking water as well as sewage is important to get information about the contamination of the water cycle. Currently, these time-consuming investigations require special equipment, like for example hyphenated mass spectrometry. Surface plasmon resonance (SPR) is a faster alternative as it is highly sensitive to changes in the dielectric medium next to a thin metal layer and makes it a quasi-universal detector. Therefore, and due to the labelfree nature, SPR is a widely used sensing tool for real-time monitoring of molecular interactions of various analytes. SPR imaging (SPRi) has several advantages to standard surface plasmon resonance, as it allows to observe many analytes in parallel as well as the integration of referencing technologies. However, the homogenous illumination of a large area (several millimeters) with a small light source is challenging and demands new approaches. Allopurinol, a drug used to lower the blood concentration of urate and hence decrease the affection of gout, gets metabolized to oxipurinol in the body and dropped out almost entirely by urinary excretion. After wastewater treatment, concentrations of oxipurinol up to 21.7 μg•L-1 are detected. Further tracking of oxipurinol in the urban water cycle showed its presence in rivers and streams or even in groundwater. Therefore, the high biological stability of oxipurinol allows this molecule to be used as a marker for domestic wastewater in the environment. For the detection of oxipurinol by SPR graphene was used as receptive layer, as the analyte can bind via π-stacking to this surface. An SPRi technique was developed and compared to conventional SPR system for the detection of oxipurinol.}, language = {en} } @inproceedings{HauslerRothAumeretal., author = {Hausler, Peter and Roth, Carina and Aumer, F. and Vitzthumecker, Thomas and Genslein, Christa and Hirsch, Thomas and Bierl, Rudolf}, title = {Miniaturisiertes Sensorsystem zur Oberfl{\"a}chenplasmonenresonanzspektroskopie}, series = {118. Jahrestagung der deutschen Gesellschaft f{\"u}r angewandte Optik (DGaO), 6.-10. Juni 2017, Dresden}, booktitle = {118. Jahrestagung der deutschen Gesellschaft f{\"u}r angewandte Optik (DGaO), 6.-10. Juni 2017, Dresden}, abstract = {Die Oberfl{\"a}chenplasmonenresonanzspektroskopie (SPR) wird aufgrund ihrer Vorz{\"u}ge der zerst{\"o}rungs- und markierungsfreien Messung, sowie der hohen Sensitivit{\"a}t sehr erfolgreich im Labormaßstab eingesetzt. Aufgrund der hohen Kosten geschieht dies bislang haupts{\"a}chlich in der Bioanalytik und dem Wirkstoffscreening. Gezeigt wird ein Ansatz, mit dem diese Technologie auf ein ultrakompaktes, kosteng{\"u}nstiges Sensorsystem {\"u}bertragen wird, welches in der Lage ist, hoch-sensitiv {\"A}nderungen im Brechungsindex von 10-6 Einheiten (RIU) zu detektieren. F{\"u}r Wasser bewirkt eine Temperaturschwankung von 1 K bereits eine {\"A}nderung von 1 mRIU. Daher wird durch ein integriertes Referenzsystem, sowie die Miniaturisierung erreicht, dass das System gegen{\"u}ber Temperaturschwankungen, weitestgehend stabil ist. In dem MOEMS wird anstatt der konventionellen 1-Punkt bzw. 2-Punkt Messung ein bildgebendes Verfahren angewendet. Die Sensorfl{\"a}che von 15 x 15 mm wird dabei mit einem handels{\"u}blichen 4 Mio. Pixel CMOS Sensor ausgewertet. Um verl{\"a}ssliche Datenpunkte zu erhalten ben{\"o}tigt man eine Fl{\"a}che von 10 x 10 Pixel. Demzufolge k{\"o}nnen auf dem Sensor theoretisch bis zu 40.000 Sensorspots parallel ausgewertet werden.}, language = {de} } @inproceedings{HauslerGensleinRothetal., author = {Hausler, Peter and Genslein, Christa and Roth, Carina and Vitzthumecker, Thomas and Hirsch, Thomas and Bierl, Rudolf}, title = {Miniaturized Surface Plasmon Resonance based Sensor System}, series = {Proceedings of the 6th International Conference on Photonics, Optics and Laser Technology - PHOTOPTICS, Funchal, Madeira, Portugal}, booktitle = {Proceedings of the 6th International Conference on Photonics, Optics and Laser Technology - PHOTOPTICS, Funchal, Madeira, Portugal}, publisher = {SciTePress}, isbn = {978-989-758-286-8}, doi = {10.5220/0006555400630066}, pages = {63 -- 66}, abstract = {We describe the miniaturization of the Surface Plasmon Resonance (SPR) technology which mainly finds its applications in pharmaceutical screening and biotechnology so far. SPR spectroscopy is a label-free, non-destructive and highly sensitive measurement principle detecting changes in the refractive index in striking distance to a gold surface. A transfer of this technology to a miniaturized sensor will broaden the range of possible applications. A promising feature which is included in the miniaturized system is the angle-dependent recording of the SPR signals without moving parts. Commercial SPR assays are mainly working with a small number of sensing spots. In contrast, the SPR imaging system shown here will allow to use an array of many sensing spots. In combination with chemical receptors designed as an artificial nose, the simultaneous detection of many analytes is envisioned for future applications.}, language = {en} } @article{GensleinHauslerKirchneretal., author = {Genslein, Christa and Hausler, Peter and Kirchner, Eva-Maria and Bierl, Rudolf and Baeumner, Antje J. and Hirsch, Thomas}, title = {Graphene-enhanced plasmonic nanohole arrays for environmental sensing in aqueous samples}, series = {Beilstein Journal of Nanotechnology}, journal = {Beilstein Journal of Nanotechnology}, number = {7}, doi = {10.3762/bjnano.7.150}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:355-epub-398623}, pages = {1564 -- 1573}, abstract = {The label-free nature of surface plasmon resonance techniques (SPR) enables a fast, specific, and sensitive analysis of molecular interactions. However, detection of highly diluted concentrations and small molecules is still challenging. It is shown here that in contrast to continuous gold films, gold nanohole arrays can significantly improve the performance of SPR devices in angle-dependent measurement mode, as a signal amplification arises from localized surface plasmons at the nanostructures. This leads consequently to an increased sensing capability of molecules bound to the nanohole array surface. Furthermore, a reduced graphene oxide (rGO) sensor surface was layered over the nanohole array. Reduced graphene oxide is a 2D nanomaterial consisting of sp2-hybridized carbon atoms and is an attractive receptor surface for SPR as it omits any bulk phase and therefore allows fast response times. In fact, it was found that nanohole arrays demonstrated a higher shift in the resonance angle of 250-380\% compared to a continuous gold film. At the same time the nanohole array structure as characterized by its diameter-to-periodicity ratio had minimal influence on the binding capacity of the sensor surface. As a simple and environmentally highly relevant model, binding of the plasticizer diethyl phthalate (DEP) via π-stacking was monitored on the rGO gold nanohole array realizing a limit of detection of as low as 20 nM. The concentration-dependent signal change was studied with the best performing rGO-modified nanohole arrays. Compared to continuous gold films a diameter-to-periodicity ratio (D/P) of 0.43 lead to a 12-fold signal enhancement. Finally, the effect of environmental waters on the sensor was evaluated using samples from sea, lake and river waters spiked with analytically relevant amounts of DEP during which significant changes in the SPR signal are observed. It is expected that this concept can be successfully transferred to enhance the sensitivity in SPR sensors.}, language = {en} } @article{SokolowskiTintenBlomeBlumsetal., author = {Sokolowski-Tinten, Klaus and Blome, Christian and Blums, Juris and Dietrich, Clemens and Tarsevitch, Alexander and Horn-von Hoegen, Michael and von der Linde, Dietrich and Cavalleri, Andrea and Kammler, Martin and Uschmann, Ingo and Foerster, Eckhart}, title = {Femtosecond X-ray Diffraction Study of Large Amplitude Coherent Optical Phonons in Laser-Excited Bismuth}, series = {Conference on Lasers and Electro-Optics, 1-6 June 2003, Baltimore, Maryland}, journal = {Conference on Lasers and Electro-Optics, 1-6 June 2003, Baltimore, Maryland}, publisher = {Optical Society of America}, abstract = {Femtosecond time-resolved X-ray diffraction was used to directly study optical phonons in laser-excited Bismuth. A periodic modulation of the diffraction efficiency reveals initially coherent lattice distortions with atomic displacements of nearly 10\% of the nearest- neighbor-distance.}, language = {en} } @inproceedings{HauslerGensleinRothetal., author = {Hausler, Peter and Genslein, Christa and Roth, Carina and Hirsch, Thomas and Bierl, Rudolf}, title = {Mikro-Opto-Elektro-Mechanisches Sensorsystem zur Oberfl{\"a}chenplasmonenresonanzspektroskopie}, series = {MikroSystemTechnik Kongress 2017 : MEMS, Mikroelektronik, Systeme 23.-25. Oktober 2017 in M{\"u}nchen}, booktitle = {MikroSystemTechnik Kongress 2017 : MEMS, Mikroelektronik, Systeme 23.-25. Oktober 2017 in M{\"u}nchen}, number = {CD-ROM}, publisher = {VDE-Verlag}, address = {Berlin}, isbn = {978-3-8007-4491-6}, pages = {645 -- 647}, abstract = {Gezeigt wird die Miniaturisierung eines Messsystems f{\"u}r Oberfl{\"a}chenplasmonenresonanzspektroskopie (SPR), einer markierungs-, sowie zerst{\"o}rungsfreien als auch hoch sensitiven Technologie. Aufgrund der hohen Kosten klassischer SPR-Ger{\"a}te wird sie bisher jedoch vornehmlich in der Bio- und Medizintechnik eingesetzt. Das Messprinzip erm{\"o}glicht die Erfassung von Brechungsindex{\"a}nderungen nahe einer Oberfl{\"a}che. Der Transfer dieser Technologie von Laborger{\"a}ten hin zu einem miniaturisierten Sensorsystem senkt die Kosten, macht das System robuster und erm{\"o}glicht so ein wesentlich breiteres Anwendungsspektrum. Ein sehr vielversprechendes Merkmal des hier vorgestellten Systems ist die M{\"o}glichkeit den SPR-Effekt winkelabh{\"a}ngig zur Lichtquelle ohne bewegliche Bauteile zu verfolgen. The miniaturization of Surface Plasmon Resonance (SPR) technology, which mainly finds its applications in pharmaceutical screening and biotechnology so far, is described. SPR spectroscopy is a label-free, non destructive and highly sensitive measurement principle which is capable of detecting changes in the refractive index in striking distance to a gold surface. A transfer of this technology to a miniaturized sensor will broaden the range of possible applications. A promising feature which is included in the miniaturized system is the angle-dependent recording of the SPR signals without moving parts.}, language = {de} } @article{LindnerPipaKarpenetal., author = {Lindner, Matthias and Pipa, Andrei V. and Karpen, Norbert and Hink, R{\"u}diger and Berndt, Dominik and Foest, R{\"u}diger and Bonaccurso, Elmar and Weichwald, Robert and Friedberger, Alois and Caspari, Ralf and Brandenburg, Ronny and Schreiner, Rupert}, title = {Icing Mitigation by MEMS-Fabricated Surface Dielectric Barrier Discharge}, series = {Applied Sciences}, volume = {11}, journal = {Applied Sciences}, number = {23}, publisher = {MDPI}, address = {Basel}, doi = {10.3390/app112311106}, pages = {1 -- 17}, abstract = {Avoiding ice accumulation on aerodynamic components is of enormous importance to flight safety. Novel approaches utilizing surface dielectric barrier discharges (SDBDs) are expected to be more efficient and effective than conventional solutions for preventing ice accretion on aerodynamic components. In this work, the realization of SDBDs based on thin-film substrates by means of micro-electro-mechanical-systems (MEMS) technology is presented. The anti-icing performance of the MEMS SDBDs is presented and compared to SDBDs manufactured by printed circuit board (PCB) technology. It was observed that the 35 mu m thick electrodes of the PCB SDBDs favor surface icing with an initial accumulation of supercooled water droplets at the electrode impact edges. This effect was not observed for 0.3 mu m thick MEMS-fabricated electrodes indicating a clear advantage for MEMS-technology SDBDs for anti-icing applications. Titanium was identified as the most suitable material for MEMS electrodes. In addition, an optimization of the MEMS-SDBDs with respect to the dielectric materials as well as SDBD design is discussed.}, language = {en} } @inproceedings{GensleinHauserKirchneretal., author = {Genslein, Christa and Hauser, Peter and Kirchner, Eva-Maria and Bierl, Rudolf and Baeumner, Antje J. and Hirsch, Thomas}, title = {Detection of small molecules with surface plasmon resonance by synergistic plasmonic effects of nanostructured surfaces and graphene}, series = {SPIE Proceedings, Plasmonics in Biology and Medicine XIV, 2017, San Francisco, California}, volume = {10080}, booktitle = {SPIE Proceedings, Plasmonics in Biology and Medicine XIV, 2017, San Francisco, California}, number = {1008001F}, doi = {10.1117/12.2252256}, abstract = {Surface plasmon resonance depends on the dielectric medium at the vicinity and makes it a quasi-universal detector. Therefore, and due to the label-free nature, SPR is a widely used sensing tool for real-time monitoring molecular interactions of various analytes. However, detection of highly diluted analytes and small molecules (< 400 Da) is still challenging. Gold nanohole arrays provide plasmonic hotspots with improved surface sensitivity and 2D carbon nanomaterials enable binding near the surface. Both effects together are promising in the development of SPR sensors for the efficient determination of small molecules. Graphene is known for efficient binding of molecules with delocalized aromatic π-systems. Additionally, the electromagnetic field is locally enhanced and modulated by the interaction of graphene photonics with the plasmonics of metal nanostructures. The advantages of chemical vapor deposition (CVD) graphene over reduced graphene oxide (rGO) is illustrated by a proof of concept study. In comparison to substrates consisting of a continuous film the surface sensitivity is enhanced for a nanohole arrays and further improved for CVD graphene functionalization in contrast to rGO. The feasibility of the sensor was demonstrated for the detection of adenine down to a concentration of 0.9 μM.}, language = {en} } @inproceedings{HauslerHollerHirschetal., author = {Hausler, Peter and Holler, Sven and Hirsch, Thomas and Bierl, Rudolf}, title = {High integrated miniaturized sensor based on Surface Plasmon Resonance}, series = {International Biosensor Conference, 11th Workshop on Biosensors \& Bioanalytical Microtechniques in Environmental, Food \& Clinical Analysis, BBMEC 11, 26.-30. September 2015, Regensburg, Germany}, booktitle = {International Biosensor Conference, 11th Workshop on Biosensors \& Bioanalytical Microtechniques in Environmental, Food \& Clinical Analysis, BBMEC 11, 26.-30. September 2015, Regensburg, Germany}, language = {en} } @inproceedings{HauslerHollerHirschetal., author = {Hausler, Peter and Holler, Sven and Hirsch, Thomas and Bierl, Rudolf}, title = {Miniaturisierte Oberfl{\"a}chenplasmonenresonanz Sensorplattform}, series = {MEMS, Mikroelektronik, Systeme, MikroSystemTechnik Kongress 2015, 26.- 28. Oktober 2015, Karlsruhe, proceedings}, booktitle = {MEMS, Mikroelektronik, Systeme, MikroSystemTechnik Kongress 2015, 26.- 28. Oktober 2015, Karlsruhe, proceedings}, publisher = {VDE Verlag}, address = {Berlin}, isbn = {978-3-8007-4100-7}, language = {de} } @article{WallKrenzerWippermannetal., author = {Wall, Simone and Krenzer, Boris and Wippermann, Stefan and Sanna, Simone and Klasing, Friedrich and Hanisch-Blicharski, Anja and Kammler, Martin and Schmidt, Wolf Gero and Horn-von Hoegen, Michael}, title = {Atomistic picture of charge density wave formation at surfaces}, series = {Physical review letters}, volume = {109}, journal = {Physical review letters}, number = {18}, publisher = {APS}, doi = {10.1103/PhysRevLett.109.186101}, abstract = {We used ultrafast electron diffraction and density-functional theory calculations to gain insight into the charge density wave (CDW) formation on In/Si(111). Weak excitation by a femtosecond-laser pulse results in the melting of the CDW. The immediate freezing is hindered by a barrier for the motion of atoms during the phase transition: The melted CDW constitutes a long-lived, supercooled phase and is strong evidence for a first-order transition. The freezing into the CDW is triggered by preexisting adsorbates. Starting at these condensation nuclei, the CDW expands one dimensionally on the In/Si(111) surface, with a constant velocity of more than 80 m/s.}, language = {en} } @article{FriggeKalusKlasingetal., author = {Frigge, Tim and Kalus, Annika and Klasing, Friedrich and Kammler, Martin and Hanisch-Blicharski, Anja and Horn-von Hoegen, Michael}, title = {Nanoscale Heat Transport in Self-Organized Ge Clusters on Si(001)}, series = {MRS Online Proceedings Library}, journal = {MRS Online Proceedings Library}, publisher = {Springer}, doi = {10.1557/opl.2013.148}, pages = {45 -- 50}, abstract = {Ultrafast time resolved transmission electron diffraction (TED) in a reflection geometry was used to study the cooling behavior of self-organized, well defined nanoscale germanium hut and dome clusters on Si(001). The clusters were heated in a pump-probe scheme by fs-laser pulses. The resulting transient temperature rise was then determined from the drop in diffraction intensity caused by the Debye-Waller effect. From a cooling time of τ=177 ps we estimated a strongly reduced heat transfer compared with homogeneous films of equivalent thickness.}, language = {en} } @article{MoellenbeckHanischBlicharskiSchneideretal., author = {M{\"o}llenbeck, Simone and Hanisch-Blicharski, Anja and Schneider, Paul and Ligges, Manuel and Zhou, Ping and Kammler, Martin and Krenzer, Boris and Horn-von Hoegen, Michael}, title = {Ultra-fast Time-Resolved Electron Diffraction of Strongly Driven Phase Transitions on Silicon Surfaces}, series = {MRS Online Proceedings Library}, journal = {MRS Online Proceedings Library}, publisher = {Springer}, doi = {10.1557/PROC-1230-MM03-09}, abstract = {The dynamics of strongly driven phase transitions at surfaces are studied by ultra-fast time-resolved reflection high energy electron diffraction. The surfaces are excited by an intense fs-laser pulse (pump) and probed by an ultra-short electron pulse with variable time delay. The order-disorder phase transition from a c(4 {\~A}— 2) to a(2 {\~A}— 1) of the bare Si(001) surface shows a transient decrease of the intensity of the c(4 {\~A}— 2) spots which recovers on a time scale of a few hundred picoseconds indicating the excitation of the phase transition. On Si(111) a monolayer of Indium induces a (4 {\~A}— 1) reconstruction which undergoes a Peierls like phase transition to a (8 {\~A}— "2") reconstruction below 100 K. Upon laser excitation with a fluence of 3.4 mJ/cm 2 at a temperature of 72 K the phase transition was strongly driven. The (8 {\~A}— "2")-diffraction spots instantaneously disappears, while the intensity of the (4 {\~A}— 1)-spots increases. This increase of the (4 {\~A}— 1) spot intensity excludes an explanation by the Debye-Waller-Effect and is evidence for a true structural phase transition at a surface. {\^A}© 2010 Materials Research Society.}, language = {en} } @article{LuNicoulShymanovichetal., author = {Lu, Wei and Nicoul, Matthieu and Shymanovich, Uladzimir and Tarsevitch, Alexander and Kammler, Martin and Horn-von Hoegen, Michael and von der Linde, Dietrich and Sokolowski-Tinten, Klaus}, title = {Extreme Phonon Softening in Laser-excited Bismuth - Towards an Inverse Peierls-transition}, series = {MRS Online Proceedings Library}, volume = {1230}, journal = {MRS Online Proceedings Library}, publisher = {Springer}, doi = {10.1557/PROC-1230-MM03-05}, abstract = {Large amplitude coherent optical phonons have been investigated in laser-excited Bismuth by means of femtosecond time-resolved X-ray diffraction. For absorbed laser fluences above 2 mJ/cm2, the experimental data reveal an extreme softening of the excited A1g-mode down to frequencies of about 1 THz, only 1/3 of the unperturbed A1g-frequency. At even stronger excitation the measured diffraction signals no longer exhibit an oscillatory behavior presenting strong indication that upon intense laser-excitation the Peierls-distortion, which defines the equilibrium structure of Bismuth, can be transiently reversed.}, language = {en} } @article{HanischBlicharskiKrenzerMoellenbecketal., author = {Hanisch-Blicharski, Anja and Krenzer, Boris and M{\"o}llenbeck, Simone and Ligges, Manuel and Zhou, Ping and Kammler, Martin and Horn-von Hoegen, Michael}, title = {Transient Cooling of Ultrathin Epitaxial Bi(111)-Films on Si(111) Upon Femtosecond Laser Excitation Studied by Ultrafast Reflection High Energy Electron Diffraction}, series = {MRS Online Proceedings Library}, journal = {MRS Online Proceedings Library}, publisher = {Springer}, doi = {10.1557/PROC-1172-T04-08}, pages = {1 -- 6}, abstract = {With time resolved ultrafast electron diffraction the cooling process across the interface between a thin film and the underlying substrate was studied after excitation with short laser pulses. From the exponential decay of the surface temperature evolution a thermal boundary conductance of 1430 W/(cm2K) is determined for a 9.7 nm thin Bi(111) film on Si(111). A linear dependence between laser fluence and initial temperature rise was measured for film-thicknesses between 2.5 nm and 34.5 nm. The ratio of initial temperature rise and laser fluence for different film-thicknesses is compared to a model taking multilayer optics into account. The data agree well with this model.}, language = {en} } @article{AlFalouKammlerHornvonHoegen, author = {Al-Falou, A. A. and Kammler, Martin and Horn-von Hoegen, Michael}, title = {Strain state analysis of hetero-epitaxial systems}, series = {Europhysics Letters}, volume = {69}, journal = {Europhysics Letters}, number = {4}, publisher = {IOP}, doi = {10.1209/epl/i2004-10399-6}, pages = {570 -- 576}, abstract = {We present a new method to analyze the strain state of epitaxial hetero structures by high-resolution spot profile analysis low-energy electron diffraction. From the variation of the spot profiles with the vertical scattering vector we determine the hetero film roughness, the change of interlayer spacing due to tetragonal distortion, and the variation of the interlayer distance due to partial relaxation of the strained rough film. The practical implementation of this method is simple and can be used to determine the onset of strain-relieving defects during the growth process.}, language = {en} } @article{KammlerHornvonHoegen, author = {Kammler, Martin and Horn-von Hoegen, Michael}, title = {Low energy electron diffraction of epitaxial growth of bismuth on Si(111)}, series = {Surface Science}, volume = {576}, journal = {Surface Science}, number = {1-3}, publisher = {Elsevier}, doi = {10.1016/j.susc.2004.11.033}, pages = {56 -- 60}, abstract = {The epitaxial growth of Bi on Si(1 1 1) studied by spot profile analyzing low energy electron diffraction shows for low coverage rotationally disordered Bi cluster with preferred orientations following the threefold symmetry of the Si substrate. With further deposition the Bi cluster coalesces and the surface orientation changes from the pseudo cubic Bi(1 1 0) surface orientation of the Bi cluster into the hexagonal Bi(1 1 1) surface of the resulting Bi film.}, language = {en} } @inproceedings{SidersCavalleriTothetal., author = {Siders, C. W. and Cavalleri, Andrea and T{\´o}th, Csaba and Wilson, K. R. and Squier, Jeff A. and Barty, C. P. J. and Kammler, Martin and Sokolowski-Tinten, Klaus and Horn-von Hoegen, Michael and von der Linde, D.}, title = {Femtosecond X-ray diffraction of short-pulse irradiated semiconductors}, series = {Summaries of Papers Presented at the Lasers and Electro-Optics. CLEO '02. Technical Diges, 24-24 May 2002, Long Beach, CA, USA}, booktitle = {Summaries of Papers Presented at the Lasers and Electro-Optics. CLEO '02. Technical Diges, 24-24 May 2002, Long Beach, CA, USA}, publisher = {IEEE}, doi = {10.1109/CLEO.2002.1033997}, pages = {297 -- 298}, abstract = {Summary form only given, as follow. Ultrafast optical-pump, X-ray diffraction probe experiments are providing new ways to study transient processes including the direct observation of the atomic motion by which many solid-state processes and chemical and biochemical reactions take place. Current table-top-terawatt femtosecond laser systems provide an attractive source of few-hundred femtosecond duration bursts of angstrom-scale X-ray radiation with fluxes comparable to standard rotating anode sources. Their compact size enables time resolved structural dynamics to be studied in the small laboratory with temporal resolution better than typical molecular vibrational periods. Ultrafast structural dynamics in crystalline samples are readily studied with such systems and experiments to be discussed in this talk include ultrafast non-thermal solid-to-liquid transition in thin single-crystal Ge-111 films grown on Si-111 substrates; ultrafast non-thermal solid-to-solid transitions in bulk vanadium dioxide from a low temperature insulating phase to a high temperature metallic phase; and harmonic and anharmonic coherent acoustic dynamics in layered Ge-111/Si-111 and bulk GaAs-111 samples. Future improvements in high-average power short-pulse lasers will enable the study of a wider class of materials such as amorphous solids or liquid-phase dynamics of simple molecules, while proposed 4th generation light sources based upon single-pass X-ray free-electron lasers will permit singleshot structural determination of complex biomolecules.}, language = {en} } @article{SokolowskiTintenBlomeBlumsetal., author = {Sokolowski-Tinten, Klaus and Blome, Christian and Blums, Juris and Cavalleri, Andrea and Dietrich, Clemens and Tarasevitch, Alexander and Uschmann, Ingo and F{\"o}rster, Eckhard and Kammler, Martin and Horn-von Hoegen, Michael and von der Linde, Dietrich}, title = {Femtosecond X-ray measurement of coherent lattice vibrations near the Lindemann stability limit}, series = {Nature}, volume = {422}, journal = {Nature}, number = {6929}, publisher = {Springer}, doi = {10.1038/nature01490}, pages = {287 -- 289}, abstract = {The study of phase-transition dynamics in solids beyond a time-averaged kinetic description requires direct measurement of the changes in the atomic configuration along the physical pathways leading to the new phase. The timescale of interest is in the range 10(-14) to 10(-12) s. Until recently, only optical techniques were capable of providing adequate time resolution, albeit with indirect sensitivity to structural arrangement. Ultrafast laser-induced changes of long-range order have recently been directly established for some materials using time-resolved X-ray diffraction. However, the measurement of the atomic displacements within the unit cell, as well as their relationship with the stability limit of a structural phase, has to date remained obscure. Here we report time-resolved X-ray diffraction measurements of the coherent atomic displacement of the lattice atoms in photoexcited bismuth close to a phase transition. Excitation of large-amplitude coherent optical phonons gives rise to a periodic modulation of the X-ray diffraction efficiency. Stronger excitation corresponding to atomic displacements exceeding 10 per cent of the nearest-neighbour distance-near the Lindemann limit-leads to a subsequent loss of long-range order, which is most probably due to melting of the material.}, language = {en} } @article{HildSeifertKammleretal., author = {Hild, R. and Seifert, C. and Kammler, Martin and Meyer zu Heringdorf, Frank-Joachim and Horn-von Hoegen, Michael and Zhachuk, R.A and Olshanetsky, B.Z}, title = {Kinetics of Au induced faceting of vicinal Si(111)}, series = {Surface Science}, volume = {512}, journal = {Surface Science}, number = {1-2}, publisher = {Elsevier}, doi = {10.1016/S0039-6028(02)01666-7}, pages = {117 -- 127}, abstract = {Au induced faceting of vicinal Si(1 1 1) has been studied during adsorption at elevated temperature by spot profile analyzing of low energy electron diffraction and after quenching to room temperature by scanning tunneling microscopy. On the surfaces inclined towards five different types of facets form with increasing Au coverage at adsorption temperatures Tads below 800 °C. They are (4 4 3), (7 7 5), (5 5 3), a stepped (2 2 1), and the (3 3 1) facets. Atomic models for the (5 5 3) and (7 7 5) facet planes are proposed on the basis of high resolution STM images. At C we found the formation of an ordered step train which covers the entire surface. With further increasing Au coverage the stepped surface decomposes again into (1 1 1) terraces and step bunches. Driving force is the formation of the Si(1 1 1)-(5×2)-Au reconstruction.}, language = {en} } @article{SokolowskiTintenHornvonHoegenvonderLindeetal., author = {Sokolowski-Tinten, Klaus and Horn-von Hoegen, Michael and von der Linde, D. and Cavalleri, Andrea and Siders, C. W. and Brown, F. L. H. and Leitner, D. M. and T{\´o}th, Csaba and Squier, Jeff A. and Barty, C. P. J. and Wilson, K. R. and Kammler, Martin}, title = {Transient lattice dynamics in fs-laser-excited semiconductors probed by ultrafast X-ray diffraction}, series = {Journal de Physique IV}, volume = {11}, journal = {Journal de Physique IV}, number = {Pr2}, publisher = {EDP}, doi = {10.1051/jp4:2001290}, pages = {473 -- 477}, abstract = {A study of lattice dynamics in fs-laser-excited crystalline bulk Ge and Ge/Si-heterostructures, using time-resolved x-ray diffraction, was presented. Fast energy transport deep into the bulk of the material, coherent acoustic phonon dynamics, lattice anharmonicity, and vibrational transport across a buried interfaces were observed. Graphs showing time-dependent shifts of the centroid of the measured rocking curves in the Ge-overlayer and in the Si-substrate for different fluences, were presented.}, language = {en} } @article{SokolowskiTintenCavalleriSidersetal., author = {Sokolowski-Tinten, Klaus and Cavalleri, Andrea and Siders, C. W. and Brown, F. L. H. and Leitner, D. M. and T{\´o}th, Csaba and Kammler, Martin and Horn-von Hoegen, Michael and von der Linde, D. and Squier, Jeff A. and Barty, C. P. J. and Wilson, K. R.}, title = {Time-resolved x-ray diffraction study of ultrafast acoustic phonon dynamics in Ge/Si-heterostructures}, series = {Chemical Physics}, volume = {66}, journal = {Chemical Physics}, publisher = {Springer}, doi = {10.1007/978-3-642-56546-5_81}, pages = {281 -- 283}, abstract = {Using time-resolved x-ray diffraction the ultafast strain dynamics in fs-laserexcited Ge/Si-heterostructures has been studied. A fluence dependent, anharmonic damping of the impulsively generated acoustic phonons and vibrational transport across the buried Ge/Si-interface are observed.}, language = {en} } @inproceedings{SokolowskiTintenBlomeDietrichetal., author = {Sokolowski-Tinten, Klaus and Blome, Christian and Dietrich, Clemens and Blums, Juris and Horn-von Hoegen, Michael and von der Linde, D. and Cavalleri, Andrea and Squier, Jeff A. and Kammler, Martin}, title = {Structural dynamics in laser-excited solids investigated with femtosecond x-ray diffraction}, series = {2002 Summaries of Papers Presented at the Quantum Electronics and Laser Science Conference, 19-24 May 2002, Long Beach, CA, USA}, booktitle = {2002 Summaries of Papers Presented at the Quantum Electronics and Laser Science Conference, 19-24 May 2002, Long Beach, CA, USA}, publisher = {IEEE}, doi = {10.1109/QELS.2002.1031182}, pages = {115 -- 116}, abstract = {Summary form only given. Ultrashort x-ray pulses offer a unique combination of atomic-scale spatial and temporal resolution, which permits direct measurements of structural transients on an ultrafast time scale. Using time-resolved X-ray diffraction with femtosecond, multi-keV X-ray pulses we have studied transient lattice dynamics in optically excited semiconductors.}, language = {en} } @article{SokolowskiTintenBlomeDietrichetal., author = {Sokolowski-Tinten, Klaus and Blome, Christian and Dietrich, Clemens and Tarasevitch, A. and Horn-von Hoegen, Michael and von der Linde, D. and Cavalleri, Andrea and Squier, Jeff A. and Kammler, Martin}, title = {Femtosecond x-ray measurement of ultrafast melting and large acoustic transients}, series = {Physical review letters}, volume = {87}, journal = {Physical review letters}, publisher = {APS}, doi = {10.1103/PhysRevLett.87.225701}, abstract = {Time-resolved x-ray diffraction with ultrashort ( approximately 300 fs), multi-keV x-ray pulses has been used to study the femtosecond laser-induced solid-to-liquid phase transition in a thin crystalline layer of germanium. Nonthermal melting is observed to take place within 300-500 fs. Following ultrafast melting we observe strong acoustic perturbations evolving on a picosecond time scale.}, language = {en} } @article{SokolowskiTintenBlomeDietrichetal., author = {Sokolowski-Tinten, Klaus and Blome, Christian and Dietrich, Clemens and Tarasevitch, A. and Horn-von Hoegen, Michael and von der Linde, D. and Cavalleri, Andrea and Squier, Jeff A. and Kammler, Martin}, title = {Femtosecond time-resolved X-ray diffraction study of ultrafast structural dynamics in laser-excited solids}, series = {International Conference on Ultrafast Phenomena, 12 May 2002, Vancouver Canada}, volume = {71}, journal = {International Conference on Ultrafast Phenomena, 12 May 2002, Vancouver Canada}, publisher = {Optica Publishing Grou}, doi = {10.1007/978-3-642-59319-2_10}, pages = {36 -- 38}, abstract = {Time-resolved x-ray diffraction with sub-300 fs, multi-keV x-ray pulses was used to study ultrafast lattice dynamics in laser-irradiated germanium and bismuth. In bismuth strong excitation of optical phonons is observed prior to disordering of the material.}, language = {en} } @unpublished{TringidesConradMenzeletal.2002, author = {Tringides, Michael C. and Conrad, E. H. and Menzel, Andreas and Voss, Neil R. and Kammler, Martin and Horn-von Hoegen, Michael}, title = {Dynamics of atomic steps on Si(001) studied by temporal LEED spectroscopy [Poster]}, year = {2002}, abstract = {While surface kinetics measurements for single atom diffusion have proliferated, little work exists attempting to measure surface dynamics under equilibrium conditions. We will present our recent work on developing Temporal LEED Spectroscopy (TLS) as a dynamic probe of surfaces capable of kinetics measurements at both high temperatures and surface coverages. By tuning the diffraction to specific structural entities such as steps, islands, etc., and monitoring the diffracted signal as a function of time, dynamics information about these structures can be obtained. As an example we will present TLS results for the dynamics of step fluctuations on Si(001) [1]. We have measured activation energies and identified step-edge diffusion as the rate limiting process for 950K < T < 1130K. Although this result is in apparent disagreement with earlier work, a careful analysis, considering crossover temperatures between different microscopic processes, can reconcile the differences. 1. M. Kammler, et al., Phys. Rev. B (in press).}, language = {en} } @article{HornvonHoegenMeyerzuHeringdorfKammleretal., author = {Horn-von Hoegen, Michael and Meyer zu Heringdorf, Frank-Joachim and Kammler, Martin and Schaeffer, C. and Reinking, D. and Hofmann, K. R.}, title = {Bi surfactant mediated epitaxy of Ge on Si(111)}, series = {Thin Solid Films}, volume = {343-344}, journal = {Thin Solid Films}, publisher = {Elsevier}, doi = {10.1016/S0040-6090(98)01659-9}, pages = {579 -- 582}, abstract = {We have tested Bi for the surfactant mediated epitaxy of Ge on Si(111). Islanding of Ge is prevented and a 2D layer growth of smooth and continuous Ge films is observed. The lattice mismatch is accommodated by a periodic array of dislocations confined to the Si/Ge interface. The large covalent radius of Bi reduces the binding energy, allowing Very efficient segregation and low doping levels even at low growth temperatures. Unfortunately, this results also in a high Bi desorption flux limiting the possible growth temperatures below 600 degrees C. Consequently the Ge films show a high defect density in the order of 10(8) cm(-2) for stacking faults and 10(9) cm(-2) for dislocations which limit electron Hall mobility to values below 700 cm(2)/V s at room temperature.}, language = {en} } @article{CavalleriSidersBrownetal., author = {Cavalleri, Andrea and Siders, C. W. and Brown, F. L. H. and Leitner, D. M. and T{\´o}th, Csaba and Squier, Jeff A. and Barty, C. P. J. and Wilson, K. R. and Sokolowski-Tinten, Klaus and Horn-von Hoegen, Michael and von der Linde, D. and Kammler, Martin}, title = {Anharmonic lattice dynamics in germanium measured with ultrafast x-ray diffraction}, series = {Physical review letters}, volume = {85}, journal = {Physical review letters}, number = {3}, publisher = {APS}, doi = {10.1103/PhysRevLett.85.586}, pages = {586 -- 589}, abstract = {Damping of impulsively generated coherent acoustic oscillations in a femtosecond laser-heated thin germanium film is measured as a function of fluence by means of ultrafast x-ray diffraction. By simultaneously measuring picosecond strain dynamics in the film and in the unexcited silicon substrate, we separate anharmonic damping from acoustic transmission through the buried interface. The measured damping rate and its dependence on the calculated temperature of the thermal bath is consistent with estimated four-body, elastic dephasing times (T2) for 7-GHz longitudinal acoustic phonons in germanium.}, language = {en} } @article{SokolowskiTintenHornvonHoegenvonderLindeetal., author = {Sokolowski-Tinten, Klaus and Horn-von Hoegen, Michael and von der Linde, D. and Cavalleri, Andrea and Siders, C. W. and Brown, F. L. H. and T{\´o}th, Csaba and Squier, Jeff A. and Barty, C. P. J. and Wilson, K. R. and Kammler, Martin}, title = {Time-resolved x-ray diffraction study of ultrafast acoustic phonon dynamics in Ge/Si-heterostructures}, series = {International Conference on Ultrafast Phenomena , 9 July 2000, Charleston}, journal = {International Conference on Ultrafast Phenomena , 9 July 2000, Charleston}, publisher = {Optica}, abstract = {Using time-resolved x-ray diffraction the ultafast strain dynamics in fs-laserexcited Ge/Si-heterostructures has been studied. A fluence dependent, anharmonic damping of the impulsively generated acoustic phonons and vibrational transport across the buried Ge/Si-interface are observed.}, language = {en} } @article{SidersCavalleriSokolowskiTintenetal., author = {Siders, C. W. and Cavalleri, Andrea and Sokolowski-Tinten, Klaus and T{\´o}th, Csaba and Guo, T. and Kammler, Martin and Horn-von Hoegen, Michael and Wilson, K. R. and von der Linde, D. and Barty, C. P. J.}, title = {Detection of nonthermal melting by ultrafast X-ray diffraction}, series = {Science}, volume = {286}, journal = {Science}, number = {5443}, doi = {10.1126/science.286.5443.1340}, pages = {1340 -- 1342}, abstract = {Using ultrafast, time-resolved, 1.54 angstrom x-ray diffraction, thermal and ultrafast nonthermal melting of germanium, involving passage through nonequilibrium extreme states of matter, was observed. Such ultrafast, optical-pump, x-ray diffraction probe measurements provide a way to study many other transient processes in physics, chemistry, and biology, including direct observation of the atomic motion by which many solid-state processes and chemical and biochemical reactions take place.}, language = {en} } @article{ReinkingKammlerHoffmannetal., author = {Reinking, D. and Kammler, Martin and Hoffmann, N. and Horn-von Hoegen, Michael and Hofmann, K. R.}, title = {Fabrication of high-mobility Ge p-channel MOSFETs on Si substrates}, series = {Electronics Letters}, volume = {35}, journal = {Electronics Letters}, number = {6}, publisher = {IET}, doi = {10.1049/el:19990349}, pages = {503 -- 504}, abstract = {The first fabrication of Ge p-channel MOSFETs (p-MOSFETs) on Si substrates is reported. A CMOS compatible process based on relaxed Ge layers grown on Si(111) substrates by surfactant mediated epitaxy (SME) was used. The non-optimised low temperature process yielded normally-off Ge p-MOSFETs with record channel drift mobilities of 430 cm2/Vs}, language = {en} } @incollection{KuhnFranziusMoelleretal., author = {Kuhn, Alexander and Franzius, Jan Niklas and M{\"o}ller, Dennis and Pralle, Norbert and Reich, Franziska and Hellmuth, Ren{\´e} and Tombeil, Anne-Sophie and Wenzel, G{\"u}nter and Linner, Thomas and Schmailzl, Marc and Hu, Rongbo and Bock, Thomas and Maufroy, Christophe and Kopp, Verena and B{\"o}lke, Nico and Daub, Urban}, title = {Kompetenzzentrum f{\"u}r Baurobotik im Hochbau (CONSAS) - F{\"o}rderkennzeichen 16SV8637}, series = {Roboter f{\"u}r Assistenzfunktionen: Konzeptstudien f{\"u}r die Interaktion in der Praxis}, booktitle = {Roboter f{\"u}r Assistenzfunktionen: Konzeptstudien f{\"u}r die Interaktion in der Praxis}, isbn = {9783731512448}, pages = {169 -- 207}, language = {de} } @article{SidersCavalleriSokolowskiTintenetal., author = {Siders, C. W. and Cavalleri, Andrea and Sokolowski-Tinten, Klaus and T{\´o}th, Csaba and Guo, T. and Kammler, Martin and Horn-von Hoegen, Michael and Wilson, K. R. and von der Linde, D. and Barty, C. P. J.}, title = {Direct Observation of Ultrafast Non-thermal Melting by Ultrafast X-ray Diffraction}, series = {Ultrafast Phenomena XII}, volume = {66}, journal = {Ultrafast Phenomena XII}, publisher = {Springer}, doi = {10.1007/978-3-642-56546-5_80}, pages = {276 -- 280}, abstract = {Ultrafast nonthermal melting of femtosecond laser-irradiated germanium was observed directly for the first time using sub-picosecond, 1.54-angstrom x-ray diffraction. Such measurements allow the study of transient atomic motion fundamental to many processes in physics, chemistry, and biology.}, language = {en} }