@misc{MatosFialhoDraganoReuteretal., author = {Matos Fialho, Paula M. and Dragano, Nico and Reuter, Matthias and Metzendorf, Maria-Inti and Richter, Bernd and Richter, Matthias and Spallek, Jacob and Diehl, Katharina and Lampert, Thomas and Pischke, Claudia R.}, title = {Health inequalities during school-to-work transitions among young adults: Mapping the evidence}, series = {European Journal of Public Health}, volume = {30}, journal = {European Journal of Public Health}, number = {Supplement_5}, doi = {10.1093/eurpub/ckaa166.278}, pages = {1}, abstract = {Background School-to-work transition is a sensitive period that can have a substantial impact on health over the life course. Previous studies suggest pronounced health inequalities during this period but little is known about the determinants at the individual, meso- and macro-levels. We aim to further elucidate possible health inequalities during school-to-work transitions with a focus on multilevel determinants, e.g. evidence on potential effects of contextual and compositional factors of specific institutions involved. Methods We are currently conducting a scoping review (funded by the German Research Foundation) to map the evidence on the above mentioned topic among young adults (aged 16-24 years), following the methodological framework proposed by Arksey and {\´O}Malley and PRISMA. The literature search was performed in Ovid MEDLINE, Web of Science, ILO and NIOSH, using sensitive search strategy developed by text-analysis. Only articles published between January 2000 - February 2020 and written in English or German are considered. The selection process is conducted following a two-step approach:1) screening of titles and abstracts 2) screening of full-texts by two independent reviewers. Any discrepancies in the selection process are resolved by a third researcher. Preliminary Results Following the five stages of the methodological framework, the scoping review is currently in stage 3 (study selection-screening phase). We found 25,069 potentially relevant articles in our primary search. 15,508 articles remained after the duplicates were removed. Up to now, 8,825 papers were screened of which 7,629 were excluded and 1,176 included which qualified for full-text reading. Complete results of the scoping review will be presented at the conference. Conclusions This scoping review will improve our knowledge about the emergence and development of health inequalities during school-to-work transitions by examining health of individuals in different institutional contexts. Key messages - Improving our knowledge of health inequalities during school-to-work transitions. - the role of determinants at the individual, meso- and macro-levels during this stage will also be examined.}, language = {en} } @inproceedings{RoeskenRohrbeckCatenaetal., author = {R{\"o}sken, Liz M. and Rohrbeck, Magdalena and Catena, Alberto and Wehner, Stefan and Fischer, Christian B. and Richter, Matthias and St{\"a}dter, Matthias and Schmeißer, Dieter}, title = {Characterization of diamond-like carbon (DLC) coatings on industrial polyethylene and polyoxymethylene by SEM, AFM and NEXAFS}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, abstract = {Diamond-like carbon (DLC) coatings are often utilized to change the base properties of raw materials, e. g. to gain robust or chemically inert surfaces. Here the deposition of hard DLC layers on soft polymers is tested. The common industrial polymers polyethylene (PE) and polyoxymethylene (POM) serve as model substrates in the present work. In order to examine the effect of the carbonaceous layers on PE and POM thin diamond-like carbon films were realized via PECVD. The topography of the different coatings was detected by AFM and SEM uncovering the different influence of the substrate material, e. g. interlayer formation for PE. The composition of the surface structures were analyzed in more detail by NEXAFS, showing the hybridization of carbon atoms in chemical different surroundings from the pure polymer to the carbon coating. The comparison of carbon coated PE- and POM-composites enables valuable insights into the interaction between soft substrates and hard coatings. For the chosen settings in PECVD, POM showed incomplete coating, while on PE a very stable and robust composite has formed.}, language = {en} } @misc{StaedterMuellerRachowetal., author = {St{\"a}dter, Matthias and M{\"u}ller, Klaus and Rachow, Fabian and Richter, Matthias and Schmeißer, Dieter}, title = {Ambient pressure thermal desorption spectroscopy (AP-TDS) of NiO/SiO2 catalysts}, series = {Environmental Earth Sciences}, volume = {70}, journal = {Environmental Earth Sciences}, number = {8}, issn = {1866-6280}, doi = {10.1007/s12665-013-2835-8}, pages = {3779 -- 3784}, abstract = {The Sabatier reaction is a key process in the "power-to-gas" application which is considered to con-tribute to future chemical energy storage systems. In this contribution we focus on the catalytic active sites of a NiO catalyst supported on SiO2(NiO/SiO2) which is commonly used in the Sabatier reaction. A novel technique for the characterization of the active sites is presented and dis-cussed using thermal desorption spectroscopy at ambient pressure. This analytical tool is operated under reaction conditions and allows element specific measurements during the catalytic process of CO2 reforming towards methane. Beside the desorption experiments, XPS and XAS measurements of pristine and catalytically used samples are performed to determine the influence of the Sabatier reaction conditions on the surface structure of the catalyst.}, language = {en} } @inproceedings{RichterStaedterPaloumpaetal., author = {Richter, Matthias and St{\"a}dter, Matthias and Paloumpa, Ioanna and Schmeißer, Dieter}, title = {Multiple Auger Decay at resonant photo-excitation in carbon thin films}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, abstract = {We use resonant photoemission at the C1s edge to study the electronic structure of HOPG, graphene flakes and monolayer graphene. We find remarkable differences in the profile of the Auger decay channels, which we attribute to an additional multiple-Auger with a three-hole final state. A prerequisite for the appearance of this decay mechanism is the existence of localized excitonic states, which cause the appearance of the multiple Auger decay. Defects (pits, holes, steps and kinks) can act as localized excitonic states. We use those effects to identify the existence and the quantity of such defect states within the pi*-band regime in carbon thin films, because the intensity of the three-hole Auger decay is varying with the defect density of the carbon films. The defect-excitonic states can be either localized in the band-gap at the M-point or in case of surface defects like steps, kinks or pits even at the K-point by losing the pure sp2 character of the films. We find that the appearance of the multiple Auger decay is different for multilayer and monolayer graphene. In particular the interaction of impurities leads to broadening of the C1s core levels. The three-hole Auger decay spectroscopy is a new method to detect such contaminations with a high sensitivity.}, language = {en} } @inproceedings{StaedterRichterSchmeisser, author = {St{\"a}dter, Matthias and Richter, Matthias and Schmeißer, Dieter}, title = {Fano-Profiles in HOPG and graphene flakes}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, abstract = {We investigated the electronic structure of the valence and conduction band of HOPG by 2D resonant photoemission spectroscopy. Our aim is to understand the electronic structure of defects and inhomogeneities in graphene and related materials in more detail. From our measurements we find that the transition from the sigma-band to the pi*-band at the M-point shows a characteristic Fano-Profile. A Fano-Profile occurs as the result of the interference of the band to band transition and a parallel transition to a discrete energy level within the band gap. The theory of Fano enables us to determine the energetic location of these discrete level. It is found to be several meV above the Fermi-Energy. Additional measurements on graphene flakes lead to similar results for the sigma- to pi*-band transition and the location of the discrete energy state. With this we not only can determine the energetic states of defects but also get a better understanding of the origin of the Fano profile which is a particular detail of the resonant absorption process.}, language = {en} } @inproceedings{FischerRohrbeckWehneretal., author = {Fischer, Christian B. and Rohrbeck, Magdalena and Wehner, Stefan and Richter, Matthias and St{\"a}dter, Matthias and Schmeißer, Dieter}, title = {Interlayer formation of Diamond-Like Carbon Coatings on Polyethylene Plastic Material}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, abstract = {The coating of materials with diamond-like carbon (DLC) is a very common way to further improve and modify surface specific properties. Although DLC is frequently used as a protective coating on several substrates, the chemical and physical properties throughout the coating process on plastics are yet sparsely investigated. Different layer thicknesses of two types of protective coatings one sp3-enriched (robust, r-type) and one with more sp2-centers (flexible, f-type) have been realized on polyethylene by PECVD. Microscopic analysis showed diverse surface topographies for the two DLC-types. NEXAFS spectroscopy revealed significant details of carbon centers in chemically different neighborhood displaying a characteristic fingerprint behavior. The appropriate explanation for the current carbon deposition process is obviously the formation of an interlayer between these unequal materials. An improved understanding of hard DLC and soft polyethylene assembly is part of the present work.}, language = {en} } @inproceedings{HoffmannbeckRichterStaedteretal., author = {Hoffmannbeck, David and Richter, Matthias and St{\"a}dter, Matthias and Paloumpa, Ioanna and Henkel, Karsten and Schmeißer, Dieter}, title = {Spectroscopic and microscopic characterization of potential catalysts for the hydrogenation of CO2}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 46}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 46}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, pages = {S. 483}, abstract = {The reduction of CO2 emissions is a general demand of the society in order to avoid irreversible climate changes. We are investigating potential catalysts for the hydrogenation of CO2 in particular for its application in the so called oxyfuel combustion process. In order to understand the catalytic behavior of the investigated materials we use the techniques X-Ray Photoemission (XPS) and -absorption (XAS) Spectroscopy as well as X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The prospective of our work is to figure out the electronic and structural properties of the material and to optimize proper catalysts or design new ones for best catalytic activity. Beside the spectro-microscopic investigations the catalysts are tested under Sabatier reaction conditions in terms of activity, stability and sensitivity against poisoning. In our preliminary work we constructed a Sabatier reactor system with analytical parts based on infrared absorption and mass spectroscopy modules. First spectroscopic and catalytic results achieved on a commercially available Ru/Al2O3 catalyst will be presented.}, language = {en} } @inproceedings{RichterFriedrichPhilipetal., author = {Richter, Matthias and Friedrich, Daniel and Philip, Shine and Paloumpa, Ioanna and M{\"u}ller, Klaus and Schmeißer, Dieter}, title = {Study of P3HT/PCBM based films by NEXAFS}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 45}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 45}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, pages = {S. 194}, abstract = {In this contribution we report on investigations of the electronic structure and composition of regioregular poly(3-hexylthiophene) (P3HT) and phenyl-C61-butyric acid methyl ester (PCBM) based films by using Near Edge X-Ray Absorption Fine Structure (NEXAFS). The measurements were done at the U49/2-PGM2 beam line of BESSY II, Berlin using TEY (total electron yield) and TFY (total fluorescence yield) detection. The samples were produced by spin casting a mixture of P3HT (dissolved in chloroform) and PCBM (dissolved in chlorobenzene) on ITO (indium tin oxide) coated glass slides. Measurements of pure P3HT and PCBM show all typical excitations, whereas the blended system is a weighted superposition of the related peaks. Analyzing these weighted superposition, we observe in the surface sensitive TEY data an accumulation of P3HT, whereas in the bulk sensitive TFY signal an as expected mixture is found. We also show angular dependent NEXAFS measurements of the P3HT/PCBM blend in order to measure the orientation and distribution of the P3HT polymer. Additionally, we will show a new approach for organic solar cell application by introducing ferroelectric nanoparticles into the mixture.}, language = {en} } @misc{DasRichterTallaridaetal., author = {Das, Chittaranjan and Richter, Matthias and Tallarida, Massimo and Schmeißer, Dieter}, title = {Electronic properties of atomic layer deposited films, anatase and rutile TiO2 studied by resonant photoemission spectroscopy}, series = {Journal of Physics D: Applied Physics}, volume = {49}, journal = {Journal of Physics D: Applied Physics}, number = {27}, issn = {0022-3727}, doi = {10.1088/0022-3727/49/27/275304}, pages = {275304-1 -- 275304-17}, abstract = {The TiO2 films are prepared by atomic layer deposition (ALD) method using titanium isopropoxide precursors at 250 °C and analyzed using resonant photoemission spectroscopy (resPES). We report on the Ti2p and O1s core levels, on the valence band (VB) spectra and x-ray absorption spectroscopy (XAS) data, and on the resonant photoelectron spectroscopy (resPES) profiles at the O1s and the Ti3p absorption edges. We determine the elemental abundance, the position of the VB maxima, the partial density of states (PDOS) in the VB and in the conduction band (CB) and collect these data in a band scheme. In addition, we analyze the band-gap states as well as the intrinsic states due to polarons and charge-transfer excitations. These states are found to cause multiple Auger decay processes upon resonant excitation. We identify several of these processes and determine their relative contribution to the Auger signal quantitatively. As our resPES data allow a quantitative analysis of these defect states, we determine the relative abundance of the PDOS in the VB and in CB and also the charge neutrality level. The anatase and rutile polymorphs of TiO2 are analyzed in the same way as the TiO2 ALD layer. The electronic properties of the TiO2ALD layer are compared with the anatase and rutile polymorphs of TiO2. In our comparative study, we find that ALD has its own characteristic electronic structure that is distinct from that of anatase and rutile. However, many details of the electronic structure are comparable and we benefit from our spectroscopic data and our careful analysis to find these differences. These can be attributed to a stronger hybridization of the O2p and Ti3d4s states for the ALD films when compared to the anatase and rutile polymorphs.}, language = {en} } @incollection{BuckschFinneGohresetal., author = {Bucksch, Jens and Finne, Emily and Gohres, Hannah and Bilz, Ludwig and Moor, Irene and Richter, Matthias and Kolip, Petra}, title = {Die Methodik des HBSC-Surveys 2013/14}, series = {Schule und Gesundheit : Ergebnisse des WHO-Jugendgesundheitssurveys "Health behaviour in school-aged children"}, booktitle = {Schule und Gesundheit : Ergebnisse des WHO-Jugendgesundheitssurveys "Health behaviour in school-aged children"}, editor = {Bilz, Ludwig and Sudeck, Gorden and Bucksch, Jens and Klocke, Andreas and Kolip, Petra and Melzer, Wolfgang and Ravens-Sieberer, Ulrike and Richter, Matthias}, publisher = {Beltz Juventa}, address = {Weinheim}, isbn = {978-3-7799-1991-9}, pages = {35 -- 46}, language = {de} } @misc{MoorSpallekRichter, author = {Moor, Irene and Spallek, Jacob and Richter, Matthias}, title = {Explaining socioeconomic inequalities in self-rated health - A systematic review of the relative contribution of material, psychological and behavioural factors}, series = {Journal of Epidemiology \& Community Health}, volume = {71}, journal = {Journal of Epidemiology \& Community Health}, number = {6}, issn = {1470-2738}, doi = {10.1136/jech-2016-207589}, language = {en} } @misc{MoorLampertRathmannetal., author = {Moor, Irene and Lampert, Thomas and Rathmann, Katharina and Kuntz, Benjamin and Kolip, Petra and Spallek, Jacob and Richter, Matthias}, title = {Explaining educational inequalities in adolescent life satisfaction: Do health behaviour and gender matter}, series = {International Journal of Public Health}, volume = {59}, journal = {International Journal of Public Health}, number = {2}, issn = {1661-8564}, pages = {309 -- 317}, language = {en} } @misc{MoorRathmannStronksetal., author = {Moor, Irene and Rathmann, Katharina and Stronks, Karien and Levin, Kate and Spallek, Jacob and Richter, Matthias}, title = {Psychosocial and behavioural factors in the explanation of socioeconomic inequalities in adolescent health. A multilevel analysis in 28 European and North American countries}, series = {Journal of epidemiology and community health}, volume = {68}, journal = {Journal of epidemiology and community health}, number = {10}, issn = {1470-2738}, doi = {10.1136/jech-2014-203933}, pages = {912 -- 921}, language = {en} } @inproceedings{TschoepeDuckhornBluethgenetal., author = {Tsch{\"o}pe, Constanze and Duckhorn, Frank and Bl{\"u}thgen, Peter and Richter, Christian and Papsdorf, Gunther and Wolff, Matthias}, title = {Miniaturisiertes System zur intelligenten Signalverarbeitung}, series = {DGZFP-Jahrestagung 2017, Zerst{\"o}rungsfreie Materialpr{\"u}fung, Koblenz, 22.-24.05.2017, Kurzfassungen der Vortr{\"a}ge und Posterbeitr{\"a}ge}, booktitle = {DGZFP-Jahrestagung 2017, Zerst{\"o}rungsfreie Materialpr{\"u}fung, Koblenz, 22.-24.05.2017, Kurzfassungen der Vortr{\"a}ge und Posterbeitr{\"a}ge}, publisher = {DGZIP}, address = {Berlin}, pages = {S. 192}, language = {de} } @misc{RathmannBilzHurrelmannetal., author = {Rathmann, Katharina and Bilz, Ludwig and Hurrelmann, Klaus and Kiess, Wieland and Richter, Matthias}, title = {Is being a "small fish in a big pond" bad for students´ psychosomatic health? A multilevel study on the role of class-level school performance}, series = {BMC Public Health}, volume = {18}, journal = {BMC Public Health}, issn = {1471-2458}, doi = {10.1186/s12889-018-5977-5}, pages = {13}, abstract = {Background. Features of schools and classes are closely related to students´ health and wellbeing. However, class composition (e.g. in terms of school performance) has rarely been examined in relation to students´ health and wellbeing. This study focuses on the so called Big-Fish-Little-Pond-Effect (BFLPE), by investigating whether the level of high-performing students in classroom is negatively associated with psychosomatic complaints of students who perceive themselves as poor performers. Methods. Data were derived from the German sample of the WHO-Collaborative "Health Behaviour in School-aged Children (HBSC)" study 2013/2014. The sample included 5226 11-, 13- and 15-year-old students. Individual perceived school performance (PSP) was included (very good/good vs. average/below average PSP) at the individual student-level. At the class-level, school performance in class was generated by aggregating the share (in percentage) of students who report a very good/good PSP to the class-level, indicating the percentage of students with good/very good PSP in classroom. Using multilevel regression models, the association between class-level school performance (in percentage of students with very good/good PSP) and individual psychosomatic complaints were analyzed, stratified by students´ individual PSP. Results. Students who report average/below average PSP showed higher likelihoods of psychosomatic complaints (Odds Ratio: 1.75; 95\% Confidence Interval: 1.52-2.03) compared to counterparts with very good/good PSP. The aggregated class-level PSP was not significantly associated with psychosomatic complaints. However, in line with the BFLPE, results further revealed that students with average/below average PSP, who attend classes with a higher percentage of students who report very good/good PSP, had higher likelihoods of psychosomatic complaints (Odds Ratio: 1.91; 95\% Confidence Interval: 1.01-4.01) compared to classmates with very good/good PSP. Conclusions. This study revealed that class composition in terms of PSP was differentially associated with students´ psychosomatic complaints, depending on their individual PSP. Findings highlight the vulnerability of students with poor PSP placed in classes with a higher percentage of students with good PSP. Results of this study therefore indicate a need for initiatives for low performing students from teachers and school staff in class.}, language = {en} } @misc{RathmannHerkeBilzetal., author = {Rathmann, Katharina and Herke, Max and Bilz, Ludwig and Rimpel{\"a}, Arja and Hurrelmann, Klaus and Richter, Matthias}, title = {Class-level school performance and life satisfaction: Differential sensitivity for low- and high-performing school-aged children}, series = {International Journal of Environmental Research and Public Health}, volume = {15}, journal = {International Journal of Environmental Research and Public Health}, number = {12}, issn = {1660-4601}, doi = {10.3390/ijerph15122750}, pages = {17}, abstract = {This study investigates whether class-level school performance affects students' life satisfaction and if there are differential effects for high- and low-performing students. Data were derived from the National Educational Panel Study, including n = 5196 students (49.6\% girls), nested in 478 classes and 250 secondary schools. School performance in class was measured by aggregating individual grade point average in Mathematics and German. The study could not reveal the "big-fish-little-pond"-effect regarding students' life satisfaction but found differential effects for high- vs. low performing students. There was no significant association for low-performing students attending classes with higher class-level performance However, low-performing students revealed the lowest life satisfaction. High-performing students placed in classes with higher average performance reported lower life satisfaction compared to high-performing students in classes with lower average performance. This study provides evidence for the impact of the learning environment in class on school-aged children's life satisfaction, by highlighting the differential sensitivity of high-performing students when placed in classes with higher or lower average performance.}, language = {en} } @misc{SchroederHoebelRoicketal., author = {Schr{\"o}der, Sara Lena and Hoebel, Jens and Roick, Julia and Markert, Jenny and Spallek, Jacob and Knesebeck, Olaf von dem and Richter, Matthias}, title = {Inequalities in the utilisation of primary and specialist physicians in Europe - a systematic review}, series = {European Journal of Public Health}, volume = {29}, journal = {European Journal of Public Health}, number = {4}, issn = {1101-1262}, doi = {10.1093/eurpub/ckz186.377}, abstract = {Background: The evidence on inequalities in health clearly shows that people with lower socioeconomic status (SES) have poorer health and higher mortality. Nevertheless, generalized evidence for inequalities in healthcare is lacking. So far, the international literature was only summarised with regard to inequalities in the utilisation of disease-specific treatment. Therefore, our aim was to synthetize the literature on socioeconomic inequalities in the utilisation of primary and specialist physicians in the general population. Methods: This systematic review searched Medline und Web of Science from 2004 to 2018. Articles that reported quantitative data on the association of SES with utilisation of primary or specialist physicians in Europe were included. Title and abstract screening were performed by two independent researchers and 50 full texts are currently sifted whether they fulfil the inclusion criteria. Results: The studies analysed utilisation of physicians in terms of probability or frequency. The initial check of the studies indicates that socioeconomic inequalities in the utilisation of physicians differ between primary and specialist care. Specialist physicians were found to be visited with a higher probability and more often by the least disadvantaged in most studies. Inequalities in the utilisation of primary physicians revealed to be more diverse with a weak pattern of equally distributed probability of GP visits and more frequent utilisation by the disadvantaged. Conclusions: The preliminary results indicate that pro-rich utilisation seems to be more pronounced in visiting specialists compared to primary health care. Aiming to reduce inequalities in healthcare, public health actions might primarily focus on reaching a needs-based consultation of specialist physicians.}, language = {en} } @misc{KraljevskiDuckhornJuetal., author = {Kraljevski, Ivan and Duckhorn, Frank and Ju, Yong Chul and Tsch{\"o}pe, Constanze and Richter, Christian and Wolff, Matthias}, title = {Acoustic Resonance Recognition of Coins}, series = {2020 IEEE International Instrumentation and Measurement Technology Conference (I2MTC), 25-28 May 2020, Dubrovnik, Croatia}, journal = {2020 IEEE International Instrumentation and Measurement Technology Conference (I2MTC), 25-28 May 2020, Dubrovnik, Croatia}, publisher = {IEEE Xplore}, isbn = {978-1-7281-4460-3}, doi = {10.1109/I2MTC43012.2020.9129256}, pages = {6}, abstract = {In this study, we compare different machine learning approaches applied to acoustic resonance recognition of coins. Euro-cents and Euro-coins were classified by the sound emerging when throwing the coins onto a hard surface.The used dataset is a representative example of a small data which was collected in carefully prepared experiments.Due to the small number of coin specimens and the count of the collected observations, it was interesting to see whether deep learning methods can achieve similarly or maybe even better classification performances compared with more traditional methods.The results of the multi-class prediction of coin denominations are presented and compared in terms of balanced accuracy and Matthews Correlation Coefficient metrics. The feature analysis methods combined with the employed classifiers achieved acceptable results, despite the relatively small dataset.}, language = {en} } @inproceedings{TschoepeDuckhornRichteretal., author = {Tsch{\"o}pe, Constanze and Duckhorn, Frank and Richter, Christian and Bl{\"u}thgen, Peter and Wolff, Matthias}, title = {Intelligent Signal Processing on a Miniaturized Hardware Module}, series = {IEEE SENSORS Proceedings, Glasgow, Scotland, UK, Oct. 29 - Nov. 1, 2017}, booktitle = {IEEE SENSORS Proceedings, Glasgow, Scotland, UK, Oct. 29 - Nov. 1, 2017}, publisher = {IEEE}, address = {Piscataway, NJ}, isbn = {978-1-5090-1012-7}, doi = {10.1109/ICSENS.2017.8234023}, language = {en} } @inproceedings{TschoepeDuckhornRichteretal., author = {Tsch{\"o}pe, Constanze and Duckhorn, Frank and Richter, Christian and Bl{\"u}thgen, Peter and Wolff, Matthias}, title = {An embedded system for acoustic pattern recognition}, series = {IEEE SENSORS Proceedings, Glasgow, Scotland, UK, Oct. 29 - Nov. 1, 2017}, booktitle = {IEEE SENSORS Proceedings, Glasgow, Scotland, UK, Oct. 29 - Nov. 1, 2017}, publisher = {IEEE}, address = {Piscataway, NJ}, isbn = {978-1-5090-1012-7}, doi = {10.1109/ICSENS.2017.8234380}, pages = {3}, language = {en} } @misc{HerkeReuterMayeretal., author = {Herke, Max and Reuter, Marvin and Mayer, A. and Spallek, Jacob and Rattay, Petra and Moor, Irene and Richter, Matthias}, title = {Wie wirkt sich die sozio{\"o}konomische Komposition der Schule auf Ungleichheiten im subjektiven Wohlbefinden von Sch{\"u}lerinnen und Sch{\"u}lern in Deutschland aus?}, series = {Gesundheitswesen}, volume = {84}, journal = {Gesundheitswesen}, number = {08/09}, publisher = {Georg Thieme Verlag}, doi = {10.1055/s-0042-1753867}, pages = {826}, abstract = {Einleitung Zielsetzung des Beitrags ist es, zu untersuchen, inwiefern die sozio{\"o}konomische Komposition von Schulen mit dem Wohlbefinden von Sch{\"u}lerinnen und Sch{\"u}lern in Deutschland assoziiert ist. Konkret wurden die Assoziationen der Bildung, des Einkommens und des beruflichen Status der Eltern auf Individualebene und aggregiert auf Schulebene sowie die Interaktionen zwischen diesen Ebenen auf das subjektive Wohlbefinden von Sch{\"u}lern der Sekundarstufe I untersucht. Methoden Es wurden Daten der Startkohorte „Klasse 5" des Nationalen Bildungspanels (NEPS) herangezogen. Die Kohorte startete 2010 mit einer repr{\"a}sentativen Stichprobe von F{\"u}nftkl{\"a}sslern in Deutschland, welche j{\"a}hrlich nachverfolgt wurden. Es wurden Erhebungswellen von der f{\"u}nften bis zur neunten Klasse zusammengefasst. Damit konnten 14.265 Beobachtungen mit vollst{\"a}ndigen Angaben von 3.977 Sch{\"u}lerinnen und Sch{\"u}lern in 218 Schulen in den Analysen ber{\"u}cksichtigt werden. Mit Mixed-Models wurde getestet, ob die sozio{\"o}konomische Position auf individueller und/oder schulischer Ebene und die ebenen{\"u}bergreifende Interaktion dieser Indikatoren mit dem Wohlbefinden (adaptierter Personal Well-Being - School Children-Index) der Jugendlichen assoziiert ist. Es wurde f{\"u}r Alter, Geschlecht, Migrationshintergrund, Familienform, Schultyp und Notendurchschnitt kontrolliert. Ergebnisse Auf individueller Ebene war das elterliche Einkommen mit h{\"o}herem Wohlbefinden verbunden. Der berufliche Status der Eltern zeigte keine signifikanten Assoziationen. Auf Schulebene fanden wir einen geringen, positiven Zusammenhang zwischen dem durchschnittlichen elterlichen Einkommen und dem individuellen Wohlbefinden, aber auch einen m{\"a}ßig negativen Einfluss eines hohen Anteils hoch gebildeter Eltern auf das Wohlbefinden. In Sensitivit{\"a}tsanalysen blieben diese Zusammenh{\"a}nge auch bei separater Betrachtung dieser Indikatoren bestehen. Die Zusammenh{\"a}nge auf Individualebene wurden nicht durch die sozio{\"o}konomische Komposition von Schulen moderiert, es konnten keine signifikanten ebenen{\"u}bergreifende Interaktionen festgestellt werden. Schlussfolgerung Es wurde ein Zusammenhang der sozio{\"o}konomischen Zusammensetzung der Schule mit dem subjektiven Wohlbefinden der Jugendlichen gefunden. Internationale Befunde einer Moderation der Zusammenh{\"a}nge auf individueller Ebene durch sozio{\"o}konomische Charakteristika auf Schulebene konnten jedoch nicht repliziert werden. Die Zusammenh{\"a}nge zwischen individueller SEP und Wohlbefinden variieren somit nicht in Abh{\"a}ngigkeit von der SEP auf Schulebene. Es zeigen sich vielmehr in Teilen additive Effekte f{\"u}r die individuelle und schulische SEP.}, language = {de} } @misc{RichterChengCrumlinetal., author = {Richter, Matthias R. and Cheng, Wen-Hui and Crumlin, Ethan J. and Drisdell, Walter S. and Atwater, Harry A. and Schmeißer, Dieter and Lewis, Nathan S. and Brunschwig, Bruce S.}, title = {X‑ray Photoelectron Spectroscopy and Resonant X‑ray Spectroscopy Investigations of Interactions between Thin Metal Catalyst Films and Amorphous Titanium Dioxide Photoelectrode Protection Layers}, series = {Chemistry of Materials}, volume = {33}, journal = {Chemistry of Materials}, number = {4}, issn = {0897-4756}, doi = {10.1021/acs.chemmater.0c04043}, pages = {1265 -- 1275}, abstract = {The use of electrochemistry, X-ray photoelectron spectroscopy, and resonant X-ray spectroscopy has unlocked the paradox of interfacial hole conduction through amorphous TiO2 (a-TiO2) to deposited Ni, Ir, and Au metal catalysts. Although electrocatalysts for the oxygen-evolution reaction derived from metallic Ir and Ni have mutually similar overpotentials in alkaline media, Si/a-TiO2/Ir interfaces exhibit higher overpotentials than Si/a-TiO2/Ni interfaces. The data allow formulation of full band energy diagrams for n-Si/a-TiO2/metal interfaces for M = Ni, Ir, or Au. Although both Ni and Ir produce band bending in a-TiO2 favoring hole conduction, only Ni creates multiple states within the a-TiO2 band gap at the a-TiO2/Ni interface, which produces a quasi-metallic interface at the a-TiO2/Ni junction. Au, however, produces a flat-band interface that limits hole conduction without any new band gap states.}, language = {en} } @misc{BrinkertRichterAkayetal., author = {Brinkert, Katharina and Richter, Matthias and Akay, {\"O}mer and Giersig, Michael and Fountaine, Katherine T. and Lewerenz, Hans-Joachim}, title = {Advancing semiconductor-electrocatalyst systems: application of surface transformation films and nanosphere lithography}, series = {Faraday Discussions}, volume = {208}, journal = {Faraday Discussions}, issn = {1359-6640}, doi = {10.1039/C8FD00003D}, pages = {523 -- 535}, abstract = {Photoelectrochemical (PEC) cells offer the possibility of carbon-neutral solar fuel production through artificial photosynthesis. The pursued design involves technologically advanced III-V semiconductor absorbers coupled via an interfacial film to an electrocatalyst layer. These systems have been prepared by in situ surface transformations in electrochemical environments. High activity nanostructured electrocatalysts are required for an efficiently operating cell, optimized in their optical and electrical properties. We demonstrate that shadow nanosphere lithography (SNL) is an auspicious tool to systematically create three-dimensional electrocatalyst nanostructures on the semiconductor photoelectrode through controlling their morphology and optical properties. First results are demonstrated by means of the photoelectrochemical production of hydrogen on p-type InP photocathodes where hitherto applied photoelectrodeposition and SNL-deposited Rh electrocatalysts are compared based on their J-V and spectroscopic behavior. We show that smaller polystyrene particle masks achieve higher defect nanostructures of rhodium on the photoelectrode which leads to a higher catalytic activity and larger short circuit currents. Structural analyses including HRSEM and the analysis of the photoelectrode surface composition by using photoelectron spectroscopy support and complement the photoelectrochemical observations. The optical performance is further compared to theoretical models of the nanostructured photoelectrodes on light scattering and propagation.}, language = {en} } @misc{BrinkertRichterAkayetal., author = {Brinkert, Katharina and Richter, Matthias and Akay, {\"O}mer and Liedtke, Janine and Giersig, Michael and Fountaine, Katherine T. and Lewerenz, Hans-Joachim}, title = {Efficient Solar Hydrogen Generation in Microgravity Environment}, series = {Nature Communications}, journal = {Nature Communications}, number = {9}, issn = {2041-1723}, doi = {10.1038/s41467-018-04844-y}, abstract = {Long-term space missions require extra-terrestrial production of storable, renewable energy. Hydrogen is ascribed a crucial role for transportation, electrical power and oxygen generation. We demonstrate in a series of drop tower experiments that efficient direct hydrogen production can be realized photoelectrochemically in microgravity environment, providing an alternative route to existing life support technologies for space travel. The photoelectrochemical cell consists of an integrated catalyst-functionalized semiconductor system that generates hydrogen with current densities >15 mA/cm2 in the absence of buoyancy. Conditions are described adverting the resulting formation of ion transport blocking froth layers on the photoelectrodes. The current limiting factors were overcome by controlling the micro- and nanotopography of the Rh electrocatalyst using shadow nanosphere lithography. The behaviour of the applied system in terrestrial and microgravity environment is simulated using a kinetic transport model. Differences observed for varied catalyst topography are elucidated, enabling future photoelectrode designs for use in reduced gravity environments.}, language = {en} } @incollection{HenkelKotRichteretal., author = {Henkel, Karsten and Kot, Małgorzata and Richter, Matthias and Tallarida, Massimo and Schmeißer, Dieter}, title = {An (In Situ)² Approach: ALD and resPES Applied to Al₂O₃, HfO₂, and TiO₂ Ultrathin Films}, series = {Encyclopedia of Interfacial Chemistry: Surface Science and Electrochemistry, Vol. 3.1}, booktitle = {Encyclopedia of Interfacial Chemistry: Surface Science and Electrochemistry, Vol. 3.1}, editor = {Wandelt, Klaus}, publisher = {Elsevier}, address = {Oxford}, isbn = {978-0-12-809739-7}, doi = {10.1016/B978-0-12-409547-2.13852-1}, pages = {18 -- 26}, abstract = {Oxide surface coatings are of importance in tailoring interface properties with respect to surface passivation, adjustment of surface potentials, or providing active centers for surface reactions. In this contribution, we report about surface coatings prepared by the atomic layer deposition (ALD) method. ALD is known for its conformal growth of ultrathin, dense films which exhibit a low concentration of pinholes.}, language = {en} } @inproceedings{RichterLichtermanHuetal., author = {Richter, Matthias and Lichterman, Michael F. and Hu, Shu and Crumlin, Ethan J. and Axnanda, Stephanus and Favaro, Marco and Drisdell, Walter S. and Hussain, Zahid and Brunschwig, Bruce S. and Liu, Zhi and Lewis, Nathan S. and Lewerenz, Hans-Joachim}, title = {Experimental Approach for Determining Semiconductor/liquid Junction Energetics by Operando Ambient Pressure X-ray Photoelectron Spectroscopy}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, pages = {S. 409}, abstract = {The performance of a photoelectrochemical solar cell depends strongly on the electrochemical nature of the semiconductor/electrolyte junction [1]. Operando Ambient Pressure X-ray photoelectron spectroscopy investigation of semiconductor/liquid junctions provides quantitative understanding of the energy bands in these photoelectrochemical solar cells [2, 3, 4]. We demonstrate how OAP-XPS may be used to determine these relationships for semiconductor/liquid systems. The data can be analyzed to determine the energy relationship between the electronic energy bands in the semiconductor electrode and the redox levels in the solution. The major conditions for semiconductor-electrolyte contacts including accumulation, depletion, and Fermi-level pinning are observed, and the so-called flat-band energy can be determined. [1] Science 344 (2014) 1005; [2] Sci Rep 5 (2015) 9788; [3] Ener Sci 8 (2015) 2409; [4] J Electrochem Soc 162 (2016) H1}, language = {en} } @inproceedings{RichterLichtermanHuetal., author = {Richter, Matthias and Lichterman, Michael F. and Hu, Shu and Crumlin, Ethan J. and Axnanda, Stephanus and Favaro, Marco and Drisdell, Walter S. and Hussain, Zahid and Brunschwig, Bruce S. and Liu, Zhi and Lewis, Nathan S. and Lewerenz, Hans-Joachim}, title = {An Electrochemical, resonant Photoemission and Ambient Pressure-X-ray Photoelectron Spectroscopic Investigation of Si/TiO2/Ni/Electrolyte Interfaces}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, pages = {S. 414}, abstract = {Photoelectrochemical cells based on semiconductor-liquid interfaces provide a method of converting solar energy to electricity or fuels. Recently, we have demonstrated operational systems that involved stabilized semiconductor-liquid junctions [1]. The electrical and spectroscopic properties of the TiO2/Ni protection layer system have been investigated in contact with electrolyte solutions [2, 3, 4]. From the response of the photoelectron binding energies to variations in applied potential the energetics of the solid/electrolyte interface are elucidated. The degree of conductivity depended on the chemical state of the Ni on the TiO2 surface. The combinations of these techniques provide a powerful tool for the investigation of hybrid electrode/solution contacts. [1] Science 344 (2014) 1005; [2] Sci Rep 5 (2015) 9788; [3] Ener \& Env Sci 8 (2015) 2409; [4] J Electrochem Soc 162 (2016) H1}, language = {en} } @inproceedings{LichtermanRichterHuetal., author = {Lichterman, Michael F. and Richter, Matthias and Hu, Shu and Crumlin, Ethan J. and Axnanda, Stephanus and Favaro, Marco and Drisdell, Walter S. and Hussain, Zahid and Brunschwig, Bruce S. and Liu, Zhi and Lewis, Nathan S. and Lewerenz, Hans-Joachim}, title = {Probing the TiO2/Liquid Interface of a Photoelectrochemical Cell by X-Ray Photoelectron Spectroscopy}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, pages = {S. 414}, abstract = {Amorphous TiO2 coatings can stabilize semiconductor photoanodes such as Si, GaAs, and GaP that are otherwise unstable in aqueous media [1]. Using tender X-rays with their substantially increased inelastic mean free scattering length of photoelectrons and using the classical three-electrode potentiostatic arrangement allows one to follow of the influence of the applied potentials on the semiconductor electrode energetics such as band bending and band edge shifts directly [2, 3]. The observed shifts in binding energy with respect to the applied potential have directly revealed rectifying junction behavior on semiconducting samples. Accumulation, depletion and Fermi level pinning were observed. Additionally, the non-linear response of the core level binding energies to changes in the applied electrode potential has revealed the influence of defect-derived electronic states on the Galvani potential across the complete cell. [1] Science 344 (2014) 1005; [2] Sci Rep 5 (2015) 9788; [3] Ener \& Env Sci 8 (2015) 2409}, language = {en} } @misc{SchmeisserHaeberleRichteretal., author = {Schmeißer, Dieter and Haeberle, J{\"o}rg and Richter, Matthias and Brazda, Petr}, title = {Spin State and Satellite Structures of ε-Fe₂O₃ as determined by Resonant Photoelectron Spectroscopy}, series = {Nuclear Instruments and Methods in Physics Research B}, volume = {2015}, journal = {Nuclear Instruments and Methods in Physics Research B}, number = {364}, issn = {0168-583X}, doi = {10.1016/j.nimb.2015.08.062}, pages = {127 -- 131}, abstract = {We use resonant photoelectron spectroscopy at the Fe2p and the O1s absorption edges to report on spectroscopic investigation of Fe-oxides nanoparticles. We discuss the spectroscopic details like multiple Auger decays, satellite emission in the X-ray absorption process and the core level data. We explain these data by a novel mechanism in which the resonant excitation between Fe3d and Fe4s states are involved. This mechanism is observed when the photo-excited electron becomes polarized by the electron-hole pairs existing in the conduction and valence bands.}, language = {en} } @phdthesis{Richter, author = {Richter, Matthias}, title = {Excitons and Polarons in resonant Auger decay processes}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:co1-opus-29816}, pages = {169}, abstract = {In the framework of this thesis synchrotron radiation spectroscopy is applied to study the electronic structure of organic semiconductors, of Graphene, and of transition metal (TM) oxide water splitting catalysts (Co-PI) with emphasis on excitonic and polaronic effects. For a correct theoretical description of the electronic structure of these material classes electron-phonon and electron-electron coupling as well as polarization and excitonic effects have to be considered. Excitons and Polarons are localized in-gap states. They are known to affect the optical properties of the material. Their influence can also be revealed in the resonant Auger decay profile. Even in TM-oxides Polarons and Excitons are observed as a consequence of an oxygen 2p to TM3d charge transfer. Therefor, the following three material classes are chosen for the fundamental study of Excitons and Polarons in resonant Auger decay processes. First, the existence of localized polaronic and excitonic states is investigated for regioregular-Poly(3 hexylthiophene-2,5-diyl) (rr-P3HT) and Phenyl-C61-butyric acid methyl ester (PCBM) used as a light absorber in organic solar cells. The existence of 2D-Polarons, singlet Exciton, and triplet Exciton is demonstrated for rr-P3HT whereas for PCBM only singlet Excitons are observed. Singlet Excitons show an influence on the resonant Auger decay by a combined spectator-participator (S+P) Auger decay in the π*-band. Second, for a more detailed study of the (S+P) decay Highly Ordered Pyrolytic Graphite (HOPG) is chosen. For Graphene as a single layer of HOPG without van der Waals force another combination of Auger decays can be observed: a double spectator Auger (S+S) and a double spectator Auger-Gain (S+S)* decay. Third, Co-PI (cobalt oxide compound) is investigated. It is a TM-oxide catalyst used for the oxygen evolution reaction in photo-electrochemical cells. Self-trapped Excitons formed by resonant core electron excitation into self-trapped hole states give rise to a combined Auger decay process (S+P). For all three novel Auger decay processes {(S+P), (S+S), and (S+S)*} a model is proposed.}, language = {en} } @misc{MeyerBorislavovEckertetal., author = {Meyer, Werner and Borislavov, Borislav and Eckert, Friedrich and Richter, Christian and R{\"o}mer, Ronald and Beim Graben, Peter and Huber, Markus and Wolff, Matthias}, title = {Formalisierung und Implementierung einer adaptiven kognitiven Architektur unter Verwendung von Strukturdiagrammen}, series = {Elektronische Sprachsignalverarbeitung 2021 : Tagungsband der 32. Konferenz Berlin, 3.-5. M{\"a}rz 2021}, journal = {Elektronische Sprachsignalverarbeitung 2021 : Tagungsband der 32. Konferenz Berlin, 3.-5. M{\"a}rz 2021}, editor = {Hillmann, Stefan and Weiss, Benjamin and Michael, Thilo and M{\"o}ller, Sebastian}, publisher = {TUDpress}, address = {Dresden}, isbn = {978-3-959082-27-3}, issn = {0940-6832}, pages = {67 -- 76}, abstract = {Das Fachgebiet der Kognitiven Technischen Systeme zeichnet sich durch einen hohen Grad an Interdisziplinarit{\"a}t (z. B. Kenntnisse auf den Gebieten Biologie, Psychologie, Informatik und den Ingenieurwissenschaften) aus. Nach wie vor besteht Bedarf an einer methodischen Darstellung des Fachgebietes, bei der die theoretische Durchdringung von Zusammenh{\"a}ngen zwischen den verschiedenen Wissensgebieten zus{\"a}tzlich durch Anschaulichkeit unterst{\"u}tzt wird. Die vorliegende Arbeit stellt einen Fortschrittsbericht zur Realisierung eines Forschungs- und Experimentiersystems dar, mit dem wir dieses Anliegen unterst{\"u}tzen und {\"u}ber das wir erstmals konzeptionell in [1] berichtet haben. In diesem Beitrag folgen wir einem integrativen Ansatz zur Entwicklung einer kognitiven Architektur, mit der unter Verwendung repr{\"a}sentationaler Datenstrukturen adaptives Verhalten auf verschiedenen Zeitskalen sowie zwei wichtige Verhaltensprogramme f{\"u}r das Probleml{\"o}sen (Objektfindung, Exploration) auf der gemeinsamen Grundlage von Markov-Entscheidungsprozessen umgesetzt werden. Mit einem Kurzbericht zum Entwicklungsstand der physikalischen Experimentierumgebung und einer Zusammenfassung der bislang erreichten Ergebnisse beschließen wir den diesj{\"a}hrigen Beitrag.}, language = {de} } @misc{RichterStarkeSchmeisser, author = {Richter, Matthias and Starke, Ulrich and Schmeißer, Dieter}, title = {Multiple Auger processes in Graphene}, series = {Journal of Electron Spectroscopy and Related Phenomena}, journal = {Journal of Electron Spectroscopy and Related Phenomena}, number = {Vol. 192}, issn = {0368-2048}, doi = {10.1016/j.elspec.2013.12.009}, pages = {1 -- 6}, abstract = {Resonant Auger decay processes have been studied by resonant photoemission spectroscopy (resPES) and X-ray absorption spectroscopy (XAS) in Graphene systems. The pi*-resonance is used to identify the degree of localization of the lowest pi*-orbitals in the conduction band. Localization and lifetime of the photo-excited intermediate state cause the formation of multiple Auger processes. For the Graphene systems we identify two novel Auger decay combinations with a four hole final state: the (S+S) and the(S+S)* decay. We demonstrate that these processes are sensitive for interlayer coupling and interactions with the metallic free electrons of the substrate.}, language = {en} } @misc{RichterFriedrichSchmeisser, author = {Richter, Matthias and Friedrich, Daniel and Schmeißer, Dieter}, title = {Interlayer-exciton mediated three-hole-Auger-decay in the pi-band of highly oriented pyrolytic graphite}, series = {Physica E}, volume = {Vol. 56}, journal = {Physica E}, issn = {1386-9477}, doi = {10.1016/j.physe.2013.01.015}, pages = {441 -- 446}, abstract = {Resonant photoemission spectroscopy(resPES) is used to probe the occupied pi- and unoccupied pi*-bands of carbon thin films with particular focus on the Auger decay. Highly Oriented Pyrolytic Graphite (HOPG) is studied at the C1s edge. We find strong resonant features at 285.5 eV and 292 eV in the resPES diagram. The normal two-hole Auger decay proceeds under constant kinetic energy (451)only in the sigma*-region. In the pi*-region, however, it proceeds under 67.5° in terms of a Ebind(w) diagram. We attribute this to a multiple Auger decay with a net three hole final state. For this novel decay process we propose a model.We discuss the long lifetime of the first resonant excitation and conclude that it arises from the strong excitonic character of the first resonant state. We use HOPG as a reference system and suggest that this novel process is a tool to identify interlayer-substrate interaction of the carbon layers involved.}, language = {en} } @misc{FischerRohrbeckWehneretal., author = {Fischer, Christian B. and Rohrbeck, Magdalena and Wehner, Stefan and Richter, Matthias and Schmeißer, Dieter}, title = {Interlayer formation of diamond-like carbon coatings on industrial polyethylene: Thickness dependent surface characterization by SEM, AFM and NEXAFS}, series = {Applied Surface Science}, journal = {Applied Surface Science}, number = {271}, issn = {0169-4332}, doi = {10.1016/j.apsusc.2013.01.210}, pages = {381 -- 389}, abstract = {The coating of materials with diamond-like carbon (DLC) is a very common way to change and improve their basic characteristics. Although DLC is used on several substrates, the chemical and physical properties throughout the coating process on plastics are yet sparsely investigated. Two types of protective coatings one sp3-enriched (robust, r-type) and one with more sp2-centers (flexible, f-type) have been realized on polyethylene by PECVD deposition. SEM and AFM analysis of coated samples of DLC types revealed diverse surface topographies on different scales and images appeared even differently smoothed by the carbonaceous deposits. Grains of both DLC types are platelet-shaped and nearly double in size for the robust type indicating fundamental differences in the epitaxial DLC growth. NEXAFS spectroscopy showed significant details of carbon centers in chemically different neighborhood displaying a characteristic fingerprint behavior. Comparison of deposition models revealed a mechanism of interlayer formation which is discussed in detail. Interlayer formation is clearly the appropriate explanation of the process for the current carbon deposition between these two unequal materials. An improved understanding of hard DLC and soft polyethylene assembly is given in the presented work.}, language = {en} } @misc{RichterPaloumpaFriedrichetal., author = {Richter, Matthias and Paloumpa, Ioanna and Friedrich, Daniel and Schmeißer, Dieter}, title = {Multiple Auger Decay At Resonant Photo-Excitation In Carbon Thin Films}, series = {ECS Transactions}, volume = {50}, journal = {ECS Transactions}, number = {20}, doi = {10.1149/05020.0009ecst}, pages = {9 -- 21}, abstract = {We use resonant photoemission at the C1s edge to study the electronic structure of HOPG, graphene flakes and monolayer graphene. We find remarkable differences in the profile of the Auger decay channels, which we attribute to an additional multiple-Auger with a three-hole final state. A prerequisite for the appearance of this decay mechanism is the existence of localized excitonic states, which cause the appearance of the multiple Auger decay. We use those effects to identify the existence and the quantity of such defect states within the π*-band regime in carbon thin films, because the intensity of the three-hole Auger decay is varying with the defect density of the carbon films. We find that the appearance of the multiple Auger decay is different for multilayer and monolayer graphene. In particular the interaction of impurities leads to broadening of the C1s core levels. The three-hole Auger decay spectroscopy is a new method to detect such contaminations with a high sensitivity.}, language = {en} } @misc{RichterSchmeisser, author = {Richter, Matthias and Schmeißer, Dieter}, title = {The Co2p Oxidation State In Co-PI Catalysts}, series = {ECS Transactions}, volume = {50}, journal = {ECS Transactions}, number = {49}, doi = {10.1149/05049.0113ecst}, pages = {113 -- 126}, abstract = {The electronic structure of Cobalt based catalysts used for photocatalytic water splitting in solar cells is analyzed using synchrotron radiation photoelectron spectroscopy. The catalyst films are prepared by electrochemical deposition. We employ a X-ray photoelectron spectroscopy study to analyze the Co2p and O1s core levels,absorption edges and valence bands. We discuss our resonant data in terms of the partial density of states of the valence and conduction band. We find a difference in the Co oxidation state as a function of film thickness (deposited charge). From the relative amount of Co, O, K and P we favor the molecular cobaltate cluster-like structure as the structural motif of the Co-PI catalyst.}, language = {en} } @misc{RichterSchmeisser, author = {Richter, Matthias and Schmeißer, Dieter}, title = {Spin states in Co-PI catalysts}, series = {Applied Physics Letters}, journal = {Applied Physics Letters}, number = {102}, issn = {1077-3118}, doi = {10.1063/1.4811748}, pages = {253904-1 -- 253904-4}, abstract = {Cobalt based oxygen evolution catalysts (Co-PI, PI=electrodeposited from pH 7 phosphate) are studied by resonant photoemission spectroscopy at the Co L3 and O1s edge. For the individual Co3d states, we determine their configuration, their spin, and their energy level relative to the Fermi energy. We identify the Co divalent high spin state and the trivalent low spin state. In addition, we also find the corresponding oxygen-to-metal charge transfer states. We attribute the trivalent charge transfer state to be the active state for the oxygen evolution reaction.}, language = {en} } @inproceedings{RichterSchmeisser, author = {Richter, Matthias and Schmeißer, Dieter}, title = {The Co2p spin and oxidation state in Co-PI catalysts}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, abstract = {The electronic structure of cobalt based catalysts used for photocatalytic water splitting in solar cells is analyzed using synchrotron radiation photoelectron spectroscopy. The catalyst films are prepared by electrochemical deposition. We employ a X-ray photoelectron spectroscopy study to analyze the Co2p and O1s core levels, absorption edges and valence bands. We discuss our resonant data in terms of the partial density of states of the valence and conduction band. We find a difference in the Co oxidation state as a function of film thickness (deposited charge). From the relative amount of Co, O, K and P we favor the molecular cobaltate cluster-like structure as the structural motif of the Co-PI catalyst. Further, at resonant PES at the Co2p edge we find the Co2p partial DOS to exhibit no sharp features next to the VBM, instead there is a broad emission at around 6eV below EFerrmi. The former are found in LiCoO2 and other Co-oxide systems with a Co3+ ground state. We attribute such sharp features to the low spin (LS) configuration of Co3+ and deduce that in the Co catalysts there is no evidence for the corresponding LS contributions. Our data prove the Co2+ ground state and demonstrate that it is exclusively in the Co3d7 high spin state in the pristine catalyst films.}, language = {en} } @misc{MuellerRichterPhilipetal., author = {M{\"u}ller, Klaus and Richter, Matthias and Philip, Shine and Kunst, Manuel and Schmeißer, Dieter}, title = {Excited states in P3HT and P3HT/PCBM blends}, series = {BioNanoScience}, volume = {2}, journal = {BioNanoScience}, number = {1}, issn = {2191-1630}, pages = {42 -- 51}, language = {en} } @misc{RichterFriedrichSchmeisser, author = {Richter, Matthias and Friedrich, Daniel and Schmeißer, Dieter}, title = {Valence and Conduction band states of PCBM as probed by photoelectron spectroscopy at resonant excitation}, series = {BioNanoScience}, volume = {2}, journal = {BioNanoScience}, number = {1}, issn = {2191-1630}, pages = {59 -- 65}, language = {en} } @misc{MuellerRichterFriedrichetal., author = {M{\"u}ller, Klaus and Richter, Matthias and Friedrich, Daniel and Paloumpa, Ioanna and Kramm, Ulrike Ingrid and Schmeißer, Dieter}, title = {Spectroscopic characterization of Cobalt-Phthalocyanine electrocatalysts for fuel cell applications}, series = {Solid State Ionics}, journal = {Solid State Ionics}, number = {216}, issn = {1872-7689}, doi = {10.1016/j.ssi.2011.12.013}, pages = {78 -- 82}, abstract = {For polymer-electrolyte-membrane fuel cells (PEM-FC), platinumcatalysts on carbon based substrates are state of the art, due to high electrochemical activity and chemical stability in acid electrolytes. High costs of platinum force investigations of alternative catalysts. With respect to the oxygen reduction reaction, possible candidates are transition metal (TM) complexes like TM-porphyrines or TM-phthalocyanines. Pyrolysis on carbon based substrates improves the catalytic activity. Highest activities were found for Fe or Co as transition metal centers. We present results of the pyrolysis of Co-phthalocyanine (CoPc) on carbon black. Besides an investigation of morphology by scanning electron microscopy (SEM) and chemical composition by energy dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS) during pyrolysis, we present a near edge X-ray absorption fine structure (NEXAFS) study of the chemical composition for the related annealing steps. This investigation is accompanied by an electrochemical characterization of the catalytic activity and selectivity. The XPS and NEXAFS data indicate a decomposition of the CoN4(chelate-) complex during pyrolysis. The N1s data for 800 °C show graphite-like, formally pyrrolic and pyridinic like features, without any significant contri-bution of Co. The Co2p data for both, XPS and NEXAFS are dominated by CoO/Co2O3. It can be concluded that during the pyrolysis cobalt particles are formed by the disintegration of CoN4-centers, after pyrolysis these par-ticles become oxidized upon contact with air.}, language = {en} } @inproceedings{RichterFriedrichSchmeisser, author = {Richter, Matthias and Friedrich, Daniel and Schmeißer, Dieter}, title = {Multiple Auger decay at resonant photo-excitation in carbon thin films}, series = {Meeting Abstracts-Electrochemical Society, Pacific Rim Meeting on Electrochemical and Solid-State Science, Honolulu, 2012}, booktitle = {Meeting Abstracts-Electrochemical Society, Pacific Rim Meeting on Electrochemical and Solid-State Science, Honolulu, 2012}, publisher = {The Electrochemical Society}, pages = {3509}, language = {en} } @inproceedings{RichterSchmeisser, author = {Richter, Matthias and Schmeißer, Dieter}, title = {The Co2p oxidation state in Co-PI catalysts}, series = {Meeting Abstracts-Electrochemical Society, Pacific Rim Meeting on Electrochemical and Solid-State Science, Honolulu, 2012}, booktitle = {Meeting Abstracts-Electrochemical Society, Pacific Rim Meeting on Electrochemical and Solid-State Science, Honolulu, 2012}, publisher = {The Electrochemical Society}, pages = {1803}, language = {en} } @inproceedings{SchmeisserRichterTallarida, author = {Schmeißer, Dieter and Richter, Matthias and Tallarida, Massimo}, title = {Intrinsic defects in TiO2 to explain resistive switching devices}, series = {Frontiers in Electronic Materials: A Collection of Extended Abstracts of the Nature Conference Frontiers in Electronic Materials, June 17 to 20 2012, Aachen, Germany}, booktitle = {Frontiers in Electronic Materials: A Collection of Extended Abstracts of the Nature Conference Frontiers in Electronic Materials, June 17 to 20 2012, Aachen, Germany}, editor = {Heber, J{\"o}rg and Schlom, Darrell and Tokura, Yoshinori and Waser, Rainer and Wuttig, Matthias}, publisher = {Wiley-VCH}, address = {Weinheim}, isbn = {978-3-527-41191-7}, doi = {10.1002/9783527667703.ch45}, pages = {255 -- 256}, language = {en} } @inproceedings{PhilipMuellerRichteretal., author = {Philip, Shine and M{\"u}ller, Klaus and Richter, Matthias and Kunst, Marinus and Schmeißer, Dieter}, title = {Study of excited states and a model for exciton-polaron interaction in P3HT}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 47}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 47}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, abstract = {Organic semiconductors efficiently harvest light in the region of the solar spectrum due to a high absorption/extinction coefficient.In our work we study the electronic structure and the charge carrier dynamics of polymeric organic semiconductor regioregular poly(3-hexylthiophen-2,5-diyl) (P3HT), an ideal p-type semiconductor and a widely used conjugated polymer, and blends with the fullerene derivative phenyl-C61-butyric acid methyl ester (PCBM), an electron acceptor material. The study was done with the help of time resolved microwave conductivity (TRMC) for contactless investigation of bulk carrier dynamics, optical spectroscopy, ultraviolet photoelectron spectroscopy(UPS) and high resolution X-ray absorption spectroscopy(XAS) which investigates excited states of rr-P3HT. From the data obtained we could infer the positions of the valence and conduction band, the existence of two excitons as well as the co-existence of one dimensional and two dimensional polarons. Based on our spectroscopic data we propose a model in which the scattering of virtual polarons and excitons are shown to create mobile polaronic charge carriers.}, language = {en} } @inproceedings{RohrbeckFischerWehneretal., author = {Rohrbeck, Magdalena and Fischer, Christian B. and Wehner, Stefan and Richter, Matthias and Schmeißer, Dieter}, title = {Diamond-Like Carbon Coatings on Industrial Polyethylene Surfaces}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 47}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 47}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, abstract = {Synthetic materials are used in a wide variety of fields. Depending on the intended application the plastic material must meet specific requirements. Since the material always interacts with its environment, particular attention is required regarding the surface. Possible damage of the plastic material and further risks could be caused by the adhesion of bacteria, biofilm formation and encrustations. Therefore, bacteria-repellent coatings and surface-modified materials that allow for an effective removal of adhered bacteria are of extremely high interest for many applications. In this study Polyethylene (PE) is chosen as simplest model for relevant plastic materials. Surface modification of PE samples is accomplished by plasma-deposited diamond-like carbon (DLC) coatings to achieve increased abrasion strength and bacterial resistance. Two types of nanometer-scaled DLC films with different layer thicknesses are compared by multiscale microscopic analysis. Further spectroscopic measurements with synchrotron radiation are performed. These results will provide an enhanced understanding of layer formation at the interface between the basic plastic material and the DLC coating and will possibly lead to optimal parameters for the surface coating to achieve improved product characteristics.}, language = {en} } @inproceedings{RichterFriedrichSchmeisser, author = {Richter, Matthias and Friedrich, Daniel and Schmeißer, Dieter}, title = {3h-Auger decay in the π-band of HOPG}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 47}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 47}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, abstract = {In this contribution we report on the electronic structure of highly oriented pyrolitic graphite (HOPG). HOPG is a model system because of the clear separation between π- and σ-bands in the valence band regime. X-ray based measurements were done at the U49/2-PGM2 beam line at BESSYII in Berlin. The resonant photoemission spectra (resPES) at the carbon K-edge give a complete picture of the occupied and unoccupied states in these sp2 hybridized system. Above the K-edge the resPES data are dominated by the Auger process causing a C2p4 final state. The Auger lines appear at constant kinetic energy (spectator, 2h) or constant binding energy (participator, 1h). For the features right at the resonance we observe a different Auger decay mechanism. We attribute it to the decay out of an excitonic intermediate state with a long lifetime. It involves three valence hole states. The original primary core hole is filled by a normal KLL Auger decay. The excited electron rests in the excitonic intermediate state and decays later. We discuss the spectral features of such combined spectator-participator decays in detail which are found only close to resonance and only in the localized valence states of excitonic excitation i.e.C1s - 1π* transitions [1, 2, 3]. [1] Richter et al. (2011) BioNanoScience, submitted. [2] Michling et al. (2011) IOP C Ser Mater Sci Eng, submitted. [3] Schmidt et al. (2011) Solid State Ionics, submitted.}, language = {en} } @inproceedings{FischerRohrbeckWehneretal., author = {Fischer, Christian B. and Rohrbeck, Magdalena and Wehner, Stefan and Richter, Matthias and Schmeißer, Dieter}, title = {Diamond-Like Carbon Coatings on Selected Plastic Materials}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 47}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 47}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, abstract = {The manufacturing of synthetic materials and their wide range of use for daily life is accompanied by essential requirements. Besides the basic performance of materials such as flexibility, elasticity, fracture strength and chemical resistance, further determinants are long term stability or biocompatibility. To overcome mismatches in surface characteristics of optimal parent material they can be customized for their intended use resulting in suitable coatings for profitable applications. The determining factor for such modifications is the preservation of basic material performance in addition to the benefit of further advantages like changed adhesive, improved repellent or antibacterial behavior. Protective coatings of selected plastic materials have been realized by depositing a few layers of diamond-like carbon (DLC). The assembly of soft plastic material and robust DLC coating is important for the resulting material characteristics. The detailed understanding of materials interphasing between these unequal materials and the conjunction of carbon centers in chemically different neighborhood is part of the presented work. Results will be transferable to other plastic materials with diverse needs, e.g. energy storage devices, water treatments and coatings for everyday commodities or industrial parts.}, language = {en} } @inproceedings{RichterSchmeisser, author = {Richter, Matthias and Schmeißer, Dieter}, title = {Electronic structure and optical properties of P3HT - Evidence of 2D-polarons in P3HT}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 46}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 46}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, pages = {S. 311}, abstract = {In this contribution we report on investigations of the electronic structure and optical characteristics of poly(3-hexylthiophene) (P3HT) based films. Various techniques like NEXAFS, SRXPS, UPS, UV-VIS and FTIR were used. X-Ray based measurements were done at the U49/2-PGM2 beam line at BESSYII. The samples were produced by spin casting P3HT dissolved in chloroform and other suitable solvents on ITO (indium tin oxide) coated glass slides and silicon substrates. Regioregular-P3HT is known to form thin films with nanocrystalline lamellae. This 2D structure give rise to additional electronic excitations in photoinduced absorption measurements, which are attributed to 2D-polarons [1]. In the Total Electron Yield (surface sensitive) and Total Fluorescence Yield (bulk sensitive) NEXAFS spectra of regioregular-P3HT three additional features can be found prior to the first typical π* excitation. The nature of these features was further investigated by means of SRXPS and UPS measurements. Energy differences relative to π*-peak maximum (0.54eV, 0.87eV and 2.24eV) suggest that these features are due to 2D-polarons. This presence of polarons is further confirmed by our FTIR and UV-VIS results. [1] Osterbacka et al., Synth. Met. 116 (2001) 317}, language = {en} } @inproceedings{MbuaMuellerRichteretal., author = {Mbua, Roy and M{\"u}ller, Klaus and Richter, Matthias and Henkel, Karsten and Paloumpa, Ioanna and Schmeißer, Dieter and Kramm, Ulricke}, title = {Investigation of new Catalysts for PEM Fuel Cells}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 46}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 46}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, pages = {S. 483}, abstract = {Increasing green house emissions amplify global warming concerns worldwide. Fuel cells, based on polymer electrolyte membranes (PEM) are part of the solution to this issue. We aim at developing and testing new catalysts for fuel cells. Platinum catalysts perform best in PEM fuel cells to date but they are very expensive. For fuel cells to be perfectly applicable and economically affordable, an alternative catalyst with similar or even greater efficiency should be developed. Metal phthalocyanines are known to be good oxygen reduction catalysts and are associated with high electron transfer properties. We investigated Cobalt Phthalocyanine in its pure state mixed with Carbon Black (CoPc:Carbon Black=1:9) untreated and also after a treatment in N2 at several temperatures, up to 1000°C for 30 minutes. Results of XPS and EDX analyses reveal that the treatment at higher temperatures causes a rearrangement in the chemical states of Co, N and C atoms. Furthermore, results of cycling voltammetry (CV) analysis reveal that CoPc treated in N2 at 800°C exhibited a higher current density, in conclusion, a higher catalytic activity than the untreated CoPc.}, language = {en} }