@unpublished{CavalleriSidersTothetal., author = {Cavalleri, Andrea and Siders, Craig and Toth, Csaba and Squier, Jeff A. and Barty, C. P. J. and Wilson, K. R. and Sokolowski-Tinten, Klaus and von der Linde, Dietrich and Kammler, Martin and Horn- von Hoegen, Michael}, title = {Measurement of harmonic and anharmonic semi-conductor-lattice dynamics with ultrafast x-ray diffraction}, abstract = {Many fundamental processes in solids, such as heat transport and phase transitions involve atomic movement on ultrafast time-scales, but cannot be directly measured with visible light. Using ultrafast x-ray diffraction, atomic motion can be measured on its natural time-scale. Photo-excitation of bulk and layered semiconductors was achieved with 800-nm wavelength femtosecond laser pulses. Optical excitation triggers a chain of relaxation processes, causing rapid lattice heating, generation and propagation of stress/strain waves into the bulk and eventual anharmonic decay of coherent acoustic phonons into the thermal bath of the solid. While the first steps of carrier relaxation, excitation and decay of Raman-active optical phonons have been in the past characterized optically at surfaces, the bulk acoustic dynamics at longer times has not. We measure length scales of lattice excitation, thereby detecting ultrafast heat diffusion via fast electrons, coherent acoustic pulse propagation into the bulk or across buried interfaces and anharmonic damping of non-equilibrium acoustic phonons. The measurement is performed with sensitivity on lattice spacing of 10 femtometers (i.e., 3 nuclear diameters).}, language = {en} } @article{BiekerRoustaieSchlaaketal., author = {Bieker, Johannes and Roustaie, Farough and Schlaak, Helmut F. and Langer, Christoph and Schreiner, Rupert and Lotz, Marcel and Wilfert, Stefan}, title = {Field emission characterization of in situ deposited gold nanocones with variable cone densities}, series = {Journal of Vacuum Science and Technology B}, volume = {36}, journal = {Journal of Vacuum Science and Technology B}, number = {2}, publisher = {AIP Publishing}, doi = {10.1116/1.5009504}, abstract = {For the fabrication of field emitter cathodes with metallic nanocones, an in situ fabrication technique based on electrodeposition in an ion track etched polymer template was used. Three samples with nanocones made of gold and different cone densities were deposited on a circular electrode with a diameter of 2.5 mm, using templates with pore density of 6 × 104, 4 × 105, and 1 × 106 cones/cm2. The cones had a height of 24 μm, a base diameter between 3 and 3.75 μm, and a tip diameter below 500 nm. Integral field emission measurements revealed onset fields of down to 3.1 V/μm and average field enhancement factors of up to 1240. For one sample, the maximum emission current from the cathode reached 142.2 μA at an applied voltage of 338 V between cathode and extraction grid, which had a distance of 50 μm. To investigate the stability of the field emission current, cumulative long-term measurements were performed for over 50 h. A stable emission current of (31.0 ± 1.3) μA at an average applied voltage of 290 V (E = 5.8 V/μm) was observed. For currents above 100 μA, a decrease of the current and therefore a degradation of the emitter structures occurred.}, language = {en} } @inproceedings{DamsSchreiner, author = {Dams, Florian and Schreiner, Rupert}, title = {A high thermal resistance MEMS-based Pirani vacuum sensor chip}, series = {Smart sensors, actuators and MEMS VI : 24 - 26 April 2013, Grenoble, France / [part of SPIE microtechnologies]}, booktitle = {Smart sensors, actuators and MEMS VI : 24 - 26 April 2013, Grenoble, France / [part of SPIE microtechnologies]}, publisher = {SPIE}, address = {Bellingham, Wash.}, doi = {10.1117/12.2017345}, abstract = {The performance of thermal conductivity vacuum gauges can be improved by a well-designed geometry. The lower measurement range limit is determined by the size of the active sensing area and the thermal conduction heat losses through the supporting structures. The upper measurement range is limited by the distance between the heated element and the cold reference plane. Silicon based MEMS-technology gives the possibility to fabricate both sensing structures with suitable areas out of low thermal conductive materials and narrow gaps in order to extend the measurement range in both directions. In this work we present a MEMS-process to fabricate high thermal resistance sensor structures. The rectangular sensitive areas are anchored by four beams and are structured out of low thermal conductive PECVD-siliconnitride films with 1 µm in thickness. The metallic heating structure is completely embedded in the SiN-layer. Both sensitive area and its support beams were released from the silicon bulk material by anisotropic underetching. In this way a free-supporting structure with a gap of 150 μm to the silicon substrate was formed. The influence of the filament geometry and temperature was systematically investigated to determine the properties of the chips as thermal conductivity vacuum gauges. The temperature of the sensitive area was held constant by a self-balancing bridge circuit and the heating power was measured by a Δ-Σ-ADC. The average solid state thermal conductivity is in the order of 106WK1. The measuring range of the most sensitive structures covers 8 orders of magnitude from 105 mbar to 1000mbar.}, language = {en} } @article{KoenigGuertler, author = {Koenig, Eric and Guertler, Katherine}, title = {One Size Does Not Fit All: Individuality and Perceptions of Improvement and Satisfaction Among TE Students}, series = {English Teaching \& Learning}, volume = {45}, journal = {English Teaching \& Learning}, number = {3}, publisher = {Springer Science and Business Media}, issn = {1023-7267}, doi = {10.1007/s42321-021-00076-4}, pages = {303 -- 324}, abstract = {Academic self-regulation is a key factor for motivation and learning achievement. Yet with the large range of individual factors, this is not a one-size-fits-all proposition. This study of L2 Technical English students at two German universities explored learners' expectations and motivations, in particular regarding self-regulation and self-efficacy via the individual's time investment in self-led study. In an initial survey, learners (N=1646) reported on their English skill levels and anticipated learning habits. Complementarily, the retrospective survey investigated learners' (N=796) actual behavior during the course, their perceptions of language skill improvement, and their satisfaction. The initial survey indicates a clear understanding that time investment in self-regulated study will lead to greater improvement, an outcome confirmed in the retrospective survey. Additionally, students who invested more time in their coursework were more satisfied with their achievement, although most learners acknowledge they should have studied more. The results verify that learners recognize the nexus between self-regulation and language skill improvement, yet university students are not satisfied with their capacity to self-regulate their language learning strategies. While differences in students' skill levels and academic self-efficacy result in divergent degrees of progress, students of all types report benefits to their language skills when motivated to self-regulated study.}, language = {en} } @article{StierstorferWellnitzSteffens, author = {Stierstorfer, Johannes and Wellnitz, Felix and Steffens, Oliver}, title = {Conservation of historic building fabric through integrated building research and digital simulation}, series = {Bauphysik}, volume = {39}, journal = {Bauphysik}, number = {2}, publisher = {ERNST \& SOHN}, doi = {10.1002/bapi.201710016}, pages = {135 -- 143}, abstract = {The abbey of Weltenburg monastery, a late baroque icon, designed by the Asam brothers and today's world heritage, has been subject to a constant need for repair and restoration due to its geological, climatological, and exposed location on the banks of the river Danube. To solve the hygric problems within the church, an exceptional restoration concept has been executed in the last decade. This research project analyses and verifies the building-physical and indoor climatic effects of the restoration measures with focus on the improvement of the central space climate. With this case study the question is raised whether appropriate measures exist that allow a contemporary and sustainable usage of historic buildings with respect to the preservation of the historic building fabric.}, language = {en} } @misc{DuesbergBachmannEdleretal., author = {D{\"u}sberg, Felix and Bachmann, Michael and Edler, Simon and Pahlke, Andreas and Langer, Christoph and Prommesberger, Christian and Schreiner, Rupert and Bunert, Erik and Wendt, Cornelius and Zimmermann, Stefan}, title = {Novel Non-Radiative Electron Source}, series = {43rd International Symposium of Capillary Chromatography \& 16h GC x GC Symposium 2019}, journal = {43rd International Symposium of Capillary Chromatography \& 16h GC x GC Symposium 2019}, abstract = {Recently a non-radioactive electron capture detector based on a thermionic electron emitter has been demonstrated [1]. Using field emitter arrays (FEAs) would yield non-radioactive portable low power devices with fast switching capability. By combining FEAs with a vacuum-sealed housing and an electron transparent membrane window, such electron sources can be operated in an ambient pressure environment.}, language = {en} } @inproceedings{BerndtLindnerSchreineretal., author = {Berndt, Dominik and Lindner, Matthias and Schreiner, Rupert and Pipa, Andrei V. and Hink, R{\"u}diger and Brandenburg, Ronny and Foest, R{\"u}diger and Geils, Judith and Sander, Aljoscha and Hoffmann, Florian and Matz, Daniel and Baars, Albert and Kesel, Antonia and Max, Alexander and Caspari, Ralf}, title = {Realization of Multifunctional Surfaces Containing MEMS-based DBD Plasma Actuators and Biomimetic Structures for Flow Manipulation}, series = {AIAA Aviation 2019 Forum, 2019, Dallas}, booktitle = {AIAA Aviation 2019 Forum, 2019, Dallas}, publisher = {American Institute of Aeronautics and Astronautics, Inc}, doi = {10.2514/6.2019-2999}, language = {en} } @inproceedings{PrommesbergerLangerSchreiner, author = {Prommesberger, Christian and Langer, Christoph and Schreiner, Rupert}, title = {Stable and low noise field emission from single p-type Si-tips}, series = {International Vacuum Nanoelectronics Conference (IVNC), 31st, 2018, Kyoto, Japan}, booktitle = {International Vacuum Nanoelectronics Conference (IVNC), 31st, 2018, Kyoto, Japan}, publisher = {IEEE}, doi = {10.1109/IVNC.2018.8520018}, pages = {1-2}, abstract = {Single gated p-type Si-tips with two different tip radii were fabricated. An emission current of 2.40 μA was measured for the sharp-edged tip at a voltage of 170 V. In contrast, a stable and reproducible emission behavior was observed with an increased tip radius resulting in a pronounced saturation region between 90 V and 150 V, but merely an emission current of 0.55 μA at 150 V. More remarkable is the stable emission behavior with fluctuation of ± 4 \% during a measurement period of 30 minutes. The integral emission current in a homogeneous tip array (16 emitters) showed nearly the same I-V characteristics compared to the single tip and is therefore, most dominated by only a stable single tip in the array.}, language = {en} } @inproceedings{LindnerBerndtPrommesbergeretal., author = {Lindner, Matthias and Berndt, Dominik and Prommesberger, Christian and Langer, Christoph and Schreiner, Rupert}, title = {Field emission assisted micro plasma discharges at vacuum and atmospheric pressures}, series = {31st International Vacuum Nanoelectronics Conference (IVNC), 2018, Kyoto, Japan}, booktitle = {31st International Vacuum Nanoelectronics Conference (IVNC), 2018, Kyoto, Japan}, doi = {10.1109/IVNC.2018.8520181}, pages = {2}, abstract = {Spatially confined non-equilibrium plasmas at vacuum and atmospheric pressure in the dimensions from a few microns to one millimeter are a promising approach to the generation and maintenance of stable glow discharges. The realization of these micro-discharges or micro-plasmas enable more accurate investigations in the field of micro plasma research. We report on field emission assisted micro plasmas excited by an alternating current with frequencies up to 1 kHz. Due to the field enhancement caused by an array of Si nano-tip structures the ignition voltage of stable plasma discharges can be reduced by 30\%.}, language = {en} } @inproceedings{BerndtLindnerTschurtschenthaleretal., author = {Berndt, Dominik and Lindner, Matthias and Tschurtschenthaler, Karl and Langer, Christoph and Schreiner, Rupert}, title = {Miniaturized Plasma Actuator Flow Measurements by MEMS-Based Thermal Conductivity Sensors}, series = {MDPI Proceedings of Eurosensors 2018, 9-12 September, Graz}, volume = {Vol.13}, booktitle = {MDPI Proceedings of Eurosensors 2018, 9-12 September, Graz}, number = {2}, doi = {10.3390/proceedings2130939}, abstract = {The gasflow created by a minaturized dielectric barrier discharge (DBD) plasma actuator is measured by a MEMS-based thermal conductivity gas sensor giving an indication of flow velocity and flow direction. The possiblity of several sensors in a small area gives a far better accuracy of local flow phenomena compared to conventional sensors. This is important for a better understanding of plasma- induced flow characteristics.}, language = {en} } @inproceedings{BierlBoehmFraunhofferetal., author = {Bierl, Rudolf and Boehm, M. and Fraunhoffer, Judith and Gardeia, Armin and Mottok, J{\"u}rgen and Schneider, Ralph and Streubel, J.}, title = {"Regensburger Modell zu den P-Seminaren" - Ein Konzept zur Gestaltung der Schnittstelle Gymnasium - Hochschule und zur Praxis einer kooperativen Lehr-Lern-Didaktik f{\"u}r Informationstechnik}, series = {3rd Embedded Software Engineering Congress, 7. bis 9. Dezember, Sindelfingen}, booktitle = {3rd Embedded Software Engineering Congress, 7. bis 9. Dezember, Sindelfingen}, publisher = {Vogel Business Media}, address = {W{\"u}rzburg}, language = {de} } @inproceedings{EdlerHanschPrommesbergeretal., author = {Edler, Simon and Hansch, Walter and Prommesberger, Christian and Schreiner, Rupert}, title = {Influence of adsorbates on the performance of a field emitter array in a high voltage triode setup}, series = {International Vacuum Nanoelectronics Conference (IVNC), 31st, 2018, Kyoto, Japan}, booktitle = {International Vacuum Nanoelectronics Conference (IVNC), 31st, 2018, Kyoto, Japan}, publisher = {IEEE}, doi = {10.1109/IVNC.2018.8520214}, pages = {1-2}, abstract = {The influence of residual gas pressure on the characteristics of black-Silicon field emitter arrays in a high voltage triode setup is investigated. I-Vcharacteristics at different pressure levels show a decrease of emission current with rising pressure. This can be explained by an increase of the work function and charging of the emitter surface due to adsorbates. The initial characteristics can be restored by heating the FEA up to 110 °C during electron emission. This regeneration procedure enables an extension of the lifetime from about 20 h to 440 h at a residual gas pressure of 10 -5 mbar.}, language = {en} } @article{GeorgeAllertWeber, author = {George, Wolfgang Michael and Allert, R. and Weber, Karsten}, title = {Versorgung Sterbender im Krankenhaus Ein vom G-BA-Innovationsfonds gef{\"o}rdertes Projekt reduziert nicht indizierte Verlegungen}, series = {KU-Gesundheitsmanagement}, volume = {90}, journal = {KU-Gesundheitsmanagement}, publisher = {Mediengruppe Oberfranken - Fachverlage}, address = {Kulmbach}, issn = {2510-8409}, pages = {24 -- 27}, abstract = {W{\"u}rdevolles Sterben muss an jedem Ort m{\"o}glich sein, auch im Krankenhaus, und hier nicht nur auf einer Palliativstation. Immer noch kommt es am Lebensende zu unn{\"o}tigen, nicht dem Patientenwohl dienenden, Verlegungen vom Heim oder der eigenen Wohnung in das Krankenhaus, vom Krankenhaus bspw. in ein Hospiz oder innerhalb des Krankenhauses von einer Normal- auf die Intensivstation. Damit die Zahl vermeidbarer Verlegungen im Krankenhaus reduziert wird, wurden im Rahmen eines Projektes zur Versorgungsforschung (Avenue-Pal), gef{\"o}rdert {\"u}ber den Gemeinsamen Bundesausschuss aus dem Innovationsfonds des Bundes, Entscheidungshilfen erarbeitet.}, language = {de} } @article{WeiglFeldmeierBierletal., author = {Weigl, Stefan and Feldmeier, Florian and Bierl, Rudolf and Matysik, Frank-Michael}, title = {Photoacoustic detection of acetone in N2 and synthetic air using a high power UV LED}, series = {Sensors Actuators B Chemical}, volume = {316}, journal = {Sensors Actuators B Chemical}, number = {August}, publisher = {Elsevier}, doi = {10.1016/j.snb.2020.128109}, pages = {1 -- 11}, abstract = {The performance of a photoacoustic trace gas sensor for the detection of acetone in N2 and synthetic air is reported. The sensor system utilises an amplitude modulated UV LED. The light source has an emission maximum at 278 nm and a maximum CW output power of 300 mW according to the datasheet. Three different collimating and focusing approaches have been investigated to guide the highly divergent LED light into the acoustic resonator of the photoacoustic measurement cell. A 3D printed aluminium cell was designed to optimize light coupling by simultaneously minimizing the photoacoustic background signal generation. Hence, the diameter of the resonator was set to a comparable large diameter of 10 mm and the inner walls of the resonator were mirror polished. The additive manufacturing procedure allowed for integration of a spirally formed gas channel, enabling gas heating prior to detection. The sensor performance was investigated by measuring acetone in N2 and synthetic air at different concentrations. The UV LED current was set to 86 \% of the maximum value according to the datasheet of the light source in order to increase the lifetime and thermal stability. An Allan-Werle deviation analysis validates a stable sensor performance. The limit of detection (LoD) was determined at a 3σ noise level with a 10 s lock-in amplifier time constant by sampling data points over 20 s with a data acquisition rate of 5 Hz. LoDs of 80.8 ppbV and 19.6 ppbV were obtained for acetone in N2 and synthetic air, respectively.}, language = {en} } @article{BerndtMuggliWittweretal., author = {Berndt, Dominik and Muggli, Josef and Wittwer, Franz and Langer, Christoph and Heinrich, Stephan and Knittel, Thorsten and Schreiner, Rupert}, title = {MEMS-based thermal conductivity sensor for hydrogen gas detection in automotive applications}, series = {Sensors and Actuators A: Physical}, volume = {305}, journal = {Sensors and Actuators A: Physical}, number = {April}, publisher = {Elsevier}, doi = {10.1016/j.sna.2019.111670}, abstract = {Accurate detection of hydrogen gas in vehicle interiors is very important for the future of a fuel cell car. Since this type of gas is highly volatile and flammable, the measurement methods have to be very reliable and precise due to safety reasons. In this paper a thermal conductivity sensor for hydrogen gas detection is presented, exhibiting a lower detection limit of 2000 ppm hydrogen in laboratory air. The sensor element is realized by micro-fabrication techniques on silicon wafers. The heated filament is exposed by a selective wet etching process creating a micro-hotplate on a thin membrane. In order to minimize power consumption, the sensor is operated in pulsed mode. Hydrogen gas detection was carried out using a synthetic gas testbench. Measurements of hydrogen contents ranging from 0\% to 4\% with an increment of 0.5\% were successfully performed for ambient gas temperatures between -15°C and 84°C. Including humidity, high moisture contents have the greatest influence on thermal conductivity. This was predicted in theoretical investigations and confirmed in experiments. For evaluation, both the change in resistance ΔR as well as the time constant τ were taken as sensor output. For both quantities, the previously established theoretical relationship with thermal conductivity could be confirmed.}, language = {en} } @article{WeiglWittmannRuecketal., author = {Weigl, Stefan and Wittmann, Elisabeth and R{\"u}ck, Thomas and Bierl, Rudolf and Matysik, Frank-Michael}, title = {Effects of ambient parameters and cross-sensitivities from O2, CO2 and H2O on the photoacoustic detection of acetone in the UV region}, series = {Sensors Actuators B Chemical}, journal = {Sensors Actuators B Chemical}, number = {328}, publisher = {Elsevier}, issn = {0925-4005}, doi = {10.1016/j.snb.2020.129001}, abstract = {We present a sensitive UV LED photoacoustic setup for the detection of gaseous acetone and discuss its applicability towards breath analysis. We investigated the performance of the sensor for low acetone concentrations down to 0.1 parts per million (ppmV). The influences of temperature, flow, pressure, optical power and LED duty cycle on the measured signal have been examined. To gain a better understanding of the different effects on the photoacoustic signal, correlation analysis was applied and feature importance was determined using a large measured dataset. Furthermore, the cross-sensitivities towards O2, CO2 and H2O have been studied extensively. Finally, the sensor's performance to detect acetone between 0.1-1 ppmV within gas mixtures simulating breath exhale conditions has been investigated, too. With a limit of detection (LoD) of 12.5 parts per billion (ppbV) (3σ) measured under typical breath exhale gas mixture conditions, the sensor demonstrated a high potential for the application of acetone detection in human breath analysis.}, language = {en} } @inproceedings{HauslerJobstFischeretal., author = {Hausler, Peter and Jobst, Simon and Fischer, Johannes and Roth, Carina and Bierl, Rudolf}, title = {Homogeneous Light Source for Surface Plasmon Resonance Imaging}, series = {PHOTOPTICS 2020: proceedings of the 8th International Conference on Photonics, Optics and Laser Technology, Valletta, Malta, February 27-29, 2020}, booktitle = {PHOTOPTICS 2020: proceedings of the 8th International Conference on Photonics, Optics and Laser Technology, Valletta, Malta, February 27-29, 2020}, publisher = {SCITEPRESS - Science and Technology Publications}, doi = {10.5220/0009168701630167}, pages = {163 -- 167}, abstract = {We describe how to build a homogeneous light source for Surface Plasmon Resonance Imaging (SPRi) 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 for detecting changes in the refractive index in close vicinity of a gold surface. A transfer of this technology to a miniaturized sensor will broaden the range of possible applications. Commercial SPR assays are mainly working with a small number of sensing spots. In contrast, the SPR imaging system shown here will allow the use of an array of many sensing spots. In combination with chemical receptors designed as an artificial nose or an electronic tongue, the simultaneous detection of many analytes is envisioned. So far, lasers or other inhomogeneous light sources were used to illuminate the sensing surface, which is decreasing the systems sensitivity. We show a compact ( 300mm2) homogeneous top hat profile. The combination of a high bit-resolution camera with our new light source enables a reflectivity based surface plasmon resonance imaging system with a high refractive index unit (RIU) resolution.}, language = {en} } @inproceedings{GschossmannJobstMottoketal., author = {Gschossmann, Andreas and Jobst, Simon and Mottok, J{\"u}rgen and Bierl, Rudolf}, title = {A Measure of Confidence of Artificial Neural Network Classifiers}, series = {ARCS Workshop 2019; 32nd International Conference on Architecture of Computing Systems, 20-21 May 2019, Copenhagen, Denmark}, booktitle = {ARCS Workshop 2019; 32nd International Conference on Architecture of Computing Systems, 20-21 May 2019, Copenhagen, Denmark}, publisher = {VDE-Verlag}, address = {Berlin}, pages = {153 -- 157}, abstract = {Confidence in results of an Artificial Neural Networks (ANNs) is increased by preferring to reject data, that is not trustful, instead of risking a misclassification. For this purpose a model is proposed that is able to recognize data, which differs significantly from the training data, during inference. The proposed model observes all activations of the hidden layers, as well as input and output layers of an ANN in a grey-box view. To make ANNs more robust in safety critical applications, this model can be used to reject flawed data, that is suspected to decrease the accuracy of the model. If this information is logged during inference, it can be used to improve the model, by training it specifically with the missing information. An experiment on the MNIST dataset is conducted and its results are discussed.}, language = {en} } @inproceedings{RomanoMicklitzOlbrichetal., author = {Romano, Marco and Micklitz, Matthias and Olbrich, Florian and Bierl, Rudolf and Ehrlich, Ingo and Gebbeken, Norbert}, title = {Experimental investigation of damping properties of unidirectionally and fabric reinforces plastics by the free decay method}, series = {Proceeding of the 15th International Materials Symposium (IMSP´2014), Pamukkale University (Denizli, Turkey), 15./17. October 2014}, booktitle = {Proceeding of the 15th International Materials Symposium (IMSP´2014), Pamukkale University (Denizli, Turkey), 15./17. October 2014}, pages = {665 -- 679}, language = {en} } @inproceedings{HaugVernim, author = {Haug, Sonja and Vernim, Matthias}, title = {Ausl{\"a}ndische Hochschulabsolventen auf dem Arbeitsmarkt in Regensburg}, series = {Tagung "Besch{\"a}ftigung ausl{\"a}ndischer Hochschulabsolventen" Bundesamt f{\"u}r Migration und Fl{\"u}chtlinge, 15.05.2014, N{\"u}rnberg}, booktitle = {Tagung "Besch{\"a}ftigung ausl{\"a}ndischer Hochschulabsolventen" Bundesamt f{\"u}r Migration und Fl{\"u}chtlinge, 15.05.2014, N{\"u}rnberg}, language = {de} } @inproceedings{SilberbauerLindnerSchreiner, author = {Silberbauer, Theodor and Lindner, Matthias and Schreiner, Rupert}, title = {Charakterisierung der dielektrischen Barrierenentladung von Mikroplasmaaktuatoren in Abh{\"a}ngigkeit der Substratdicke}, series = {Intelligente Systeme und ihre Komponenten: Forschung und industrielle Anwendung : Fachbeitr{\"a}ge 2. Symposium Elektronik und Systemintegration ESI 2020}, booktitle = {Intelligente Systeme und ihre Komponenten: Forschung und industrielle Anwendung : Fachbeitr{\"a}ge 2. Symposium Elektronik und Systemintegration ESI 2020}, address = {Landshut}, pages = {64 -- 72}, language = {de} } @unpublished{SidersCavalleriTothetal., author = {Siders, Craig and Cavalleri, Andrea and Toth, Csaba and Squier Jeff A., and Barty, C. P. J. and Wilson, K. R. and Sokolowski-Tinten, Klaus and von der Linde, Dietrich and Kammler, Martin and Horn- von Hoegen, Michael}, title = {Ultrafast Nonthermal Melting of Femtosecond-laser-irradiated Germanium Measured by Ultrafast X-ray Diffraction}, abstract = {Many fundamental processes in nature, such as chemical reactions and phase transitions involve rearrangement of the constituent atoms. Such changes cannot be directly measured with visible light and occur transiently on time-scales comparable with the natural oscillation periods of atoms (femtoseconds to picoseconds). We present experiments on Ge-111 films irradiated with 100-fs 800-nm light pulses and probed by a time-delayed sub-ps x-ray pulse at 8 keV. After excitation of a dense electron-hole plasma within the 160-nm film, the ultrafast pathway of lattice disordering is measured as a function laser fluence. For close-to-threshold irradiation, inhomogeneous thermal melting, occurring via surface nucleation of the liquid phase and growth into the bulk determines the dynamics of the solid-to-liquid phase transition. For excitation at about twice the melting threshold, a nonthermal pathway, starting from a highly excited cold solid and relaxing into a hot liquid causes ultrafast melting. At long time delays, nearly perfect recrystallization of a (111) crystal is observed.}, language = {en} }