TY - GEN A1 - Matos Fialho, Paula M. A1 - Dragano, Nico A1 - Reuter, Matthias A1 - Metzendorf, Maria-Inti A1 - Richter, Bernd A1 - Richter, Matthias A1 - Spallek, Jacob A1 - Diehl, Katharina A1 - Lampert, Thomas A1 - Pischke, Claudia R. T1 - Health inequalities during school-to-work transitions among young adults: Mapping the evidence T2 - European Journal of Public Health N2 - 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 ÓMalley 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. KW - Health inequalities KW - school-to-work transition KW - young adults KW - life course Y1 - 2020 U6 - https://doi.org/10.1093/eurpub/ckaa166.278 VL - 30 IS - Supplement_5 ER - TY - CHAP A1 - Rösken, Liz M. A1 - Rohrbeck, Magdalena A1 - Catena, Alberto A1 - Wehner, Stefan A1 - Fischer, Christian B. A1 - Richter, Matthias A1 - Städter, Matthias A1 - Schmeißer, Dieter T1 - Characterization of diamond-like carbon (DLC) coatings on industrial polyethylene and polyoxymethylene by SEM, AFM and NEXAFS T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - 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. KW - Diamond-like carbon (DLC) KW - soft plolymers KW - Scanning electron microscopy (SEM) KW - Atomic foce microscopy (AFM) KW - Near-edge X-Ray absorption spectroscopy (NEXAFS) Y1 - 2014 UR - http://www.dpg-verhandlungen.de/year/2014/conference/dresden/part/ds/session/43/contribution/20?lang=en SN - 0420-0195 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - GEN A1 - Städter, Matthias A1 - Müller, Klaus A1 - Rachow, Fabian A1 - Richter, Matthias A1 - Schmeißer, Dieter T1 - Ambient pressure thermal desorption spectroscopy (AP-TDS) of NiO/SiO2 catalysts T2 - Environmental Earth Sciences N2 - 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. KW - CO2 KW - NiO KW - TDS KW - XAS KW - XPS Y1 - 2013 U6 - https://doi.org/10.1007/s12665-013-2835-8 SN - 1866-6280 VL - 70 IS - 8 SP - 3779 EP - 3784 ER - TY - CHAP A1 - Richter, Matthias A1 - Städter, Matthias A1 - Paloumpa, Ioanna A1 - Schmeißer, Dieter T1 - Multiple Auger Decay at resonant photo-excitation in carbon thin films T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - 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. KW - resonant photoelectron spectroscopy KW - Auger decay KW - multiple decay KW - carbon thin films Y1 - 2013 UR - http://www.dpg-verhandlungen.de/year/2013/conference/regensburg/part/hl/session/52/contribution/6?lang=de PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Städter, Matthias A1 - Richter, Matthias A1 - Schmeißer, Dieter T1 - Fano-Profiles in HOPG and graphene flakes T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - 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. KW - resonant photoelectron spectroscopy KW - Fano profiles KW - Graphene KW - HOPG Y1 - 2013 UR - http://www.dpg-verhandlungen.de/year/2013/conference/regensburg/part/hl/session/52/contribution/5?lang=de PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Fischer, Christian B. A1 - Rohrbeck, Magdalena A1 - Wehner, Stefan A1 - Richter, Matthias A1 - Städter, Matthias A1 - Schmeißer, Dieter T1 - Interlayer formation of Diamond-Like Carbon Coatings on Polyethylene Plastic Material T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - 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. KW - Diamond-like carbon (DLC) KW - topography KW - X-ray absorption spectroscopy KW - plasma enhanced chemical vapor deposition Y1 - 2013 UR - http://www.dpg-verhandlungen.de/year/2013/conference/regensburg/part/o/session/33/contribution/4?lang=de PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Hoffmannbeck, David A1 - Richter, Matthias A1 - Städter, Matthias A1 - Paloumpa, Ioanna A1 - Henkel, Karsten A1 - Schmeißer, Dieter T1 - Spectroscopic and microscopic characterization of potential catalysts for the hydrogenation of CO2 T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 46 N2 - 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. Y1 - 2011 UR - http://www.dpg-verhandlungen.de/year/2011/conference/dresden/part/o/session/60/contribution/123 SN - 0420-0195 SP - S. 483 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Richter, Matthias A1 - Friedrich, Daniel A1 - Philip, Shine A1 - Paloumpa, Ioanna A1 - Müller, Klaus A1 - Schmeißer, Dieter T1 - Study of P3HT/PCBM based films by NEXAFS T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 45 N2 - 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. Y1 - 2010 UR - http://www.dpg-verhandlungen.de/year/2010/conference/regensburg/part/df/session/7/contribution/4 SN - 0420-0195 SP - S. 194 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - GEN A1 - Das, Chittaranjan A1 - Richter, Matthias A1 - Tallarida, Massimo A1 - Schmeißer, Dieter T1 - Electronic properties of atomic layer deposited films, anatase and rutile TiO2 studied by resonant photoemission spectroscopy T2 - Journal of Physics D: Applied Physics N2 - 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. KW - titanium dioxide (TiO2) KW - resonant photoemission spectroscopy (resPES) KW - defect states KW - partial density of states (pDOS) KW - charge neutrality level (CNL) Y1 - 2016 U6 - https://doi.org/10.1088/0022-3727/49/27/275304 SN - 0022-3727 SN - 1361-6463 VL - 49 IS - 27 SP - 275304-1 EP - 275304-17 ER - TY - CHAP A1 - Bucksch, Jens A1 - Finne, Emily A1 - Gohres, Hannah A1 - Bilz, Ludwig A1 - Moor, Irene A1 - Richter, Matthias A1 - Kolip, Petra ED - Bilz, Ludwig ED - Sudeck, Gorden ED - Bucksch, Jens ED - Klocke, Andreas ED - Kolip, Petra ED - Melzer, Wolfgang ED - Ravens-Sieberer, Ulrike ED - Richter, Matthias T1 - Die Methodik des HBSC-Surveys 2013/14 T2 - Schule und Gesundheit : Ergebnisse des WHO-Jugendgesundheitssurveys "Health behaviour in school-aged children" Y1 - 2016 SN - 978-3-7799-1991-9 SP - 35 EP - 46 PB - Beltz Juventa CY - Weinheim ER - TY - GEN A1 - Moor, Irene A1 - Spallek, Jacob A1 - Richter, Matthias T1 - Explaining socioeconomic inequalities in self-rated health - A systematic review of the relative contribution of material, psychological and behavioural factors T2 - Journal of Epidemiology & Community Health Y1 - 2017 U6 - https://doi.org/10.1136/jech-2016-207589 SN - 1470-2738 VL - 71 IS - 6 ER - TY - GEN A1 - Moor, Irene A1 - Lampert, Thomas A1 - Rathmann, Katharina A1 - Kuntz, Benjamin A1 - Kolip, Petra A1 - Spallek, Jacob A1 - Richter, Matthias T1 - Explaining educational inequalities in adolescent life satisfaction: Do health behaviour and gender matter T2 - International Journal of Public Health Y1 - 2014 SN - 1661-8564 VL - 59 IS - 2 SP - 309 EP - 317 ER - TY - GEN A1 - Moor, Irene A1 - Rathmann, Katharina A1 - Stronks, Karien A1 - Levin, Kate A1 - Spallek, Jacob A1 - Richter, Matthias T1 - Psychosocial and behavioural factors in the explanation of socioeconomic inequalities in adolescent health. A multilevel analysis in 28 European and North American countries T2 - Journal of epidemiology and community health Y1 - 2014 U6 - https://doi.org/10.1136/jech-2014-203933 SN - 1470-2738 VL - 68 IS - 10 SP - 912 EP - 921 ER - TY - CHAP A1 - Tschöpe, Constanze A1 - Duckhorn, Frank A1 - Blüthgen, Peter A1 - Richter, Christian A1 - Papsdorf, Gunther A1 - Wolff, Matthias T1 - Miniaturisiertes System zur intelligenten Signalverarbeitung T2 - DGZFP-Jahrestagung 2017, Zerstörungsfreie Materialprüfung, Koblenz, 22.-24.05.2017, Kurzfassungen der Vorträge und Posterbeiträge Y1 - 2017 UR - https://www.google.de/url?sa=t&rct=j&q=&esrc=s&source=web&cd=5&ved=0ahUKEwiOtpCM7-zUAhXBZ1AKHXMyBQYQFghDMAQ&url=https%3A%2F%2Fjahrestagung.dgzfp.de%2FPortals%2F151%2Fdownloads%2FKufa_alles_oP%2520-%2520GESAMT%2520-%2520ohne%2520Anzeigen.pdf%3Fver%3D2017-05-19-135955-633&usg=AFQjCNGFKZug7Xf1FFhVCqafxEFIyDEIeA&cad=rja SP - S. 192 PB - DGZIP CY - Berlin ER - TY - GEN A1 - Rathmann, Katharina A1 - Bilz, Ludwig A1 - Hurrelmann, Klaus A1 - Kiess, Wieland A1 - Richter, Matthias T1 - 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 T2 - BMC Public Health N2 - 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. KW - School performance KW - Reference group effects KW - Health complaints KW - BFLPE KW - Multilevel analysis KW - HBSC Y1 - 2018 U6 - https://doi.org/10.1186/s12889-018-5977-5 SN - 1471-2458 VL - 18 ER - TY - GEN A1 - Rathmann, Katharina A1 - Herke, Max A1 - Bilz, Ludwig A1 - Rimpelä, Arja A1 - Hurrelmann, Klaus A1 - Richter, Matthias T1 - Class-level school performance and life satisfaction: Differential sensitivity for low- and high-performing school-aged children T2 - International Journal of Environmental Research and Public Health N2 - 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. KW - school performance KW - social comparision KW - life satisfaction KW - big-fish-little-pond-effect KW - multilevel analysis KW - National Educational Panel Study Y1 - 2018 U6 - https://doi.org/10.3390/ijerph15122750 SN - 1660-4601 SN - 1661-7827 VL - 15 IS - 12 ER - TY - GEN A1 - Schröder, Sara Lena A1 - Hoebel, Jens A1 - Roick, Julia A1 - Markert, Jenny A1 - Spallek, Jacob A1 - Knesebeck, Olaf von dem A1 - Richter, Matthias T1 - Inequalities in the utilisation of primary and specialist physicians in Europe - a systematic review T2 - European Journal of Public Health N2 - 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. KW - Inequalities KW - Review KW - Primary health care KW - specialist health care KW - utilization Y1 - 2019 U6 - https://doi.org/10.1093/eurpub/ckz186.377 SN - 1101-1262 SN - 1464-360X VL - 29 IS - 4 ER - TY - GEN A1 - Kraljevski, Ivan A1 - Duckhorn, Frank A1 - Ju, Yong Chul A1 - Tschöpe, Constanze A1 - Richter, Christian A1 - Wolff, Matthias T1 - Acoustic Resonance Recognition of Coins T2 - 2020 IEEE International Instrumentation and Measurement Technology Conference (I2MTC), 25-28 May 2020, Dubrovnik, Croatia N2 - 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. Y1 - 2020 SN - 978-1-7281-4460-3 SN - 978-1-7281-4461-0 U6 - https://doi.org/10.1109/I2MTC43012.2020.9129256 PB - IEEE Xplore ER - TY - CHAP A1 - Tschöpe, Constanze A1 - Duckhorn, Frank A1 - Richter, Christian A1 - Blüthgen, Peter A1 - Wolff, Matthias T1 - Intelligent Signal Processing on a Miniaturized Hardware Module T2 - IEEE SENSORS Proceedings, Glasgow, Scotland, UK, Oct. 29 - Nov. 1, 2017 Y1 - 2017 UR - http://ieeexplore.ieee.org/document/8234023/ SN - 978-1-5090-1012-7 U6 - https://doi.org/10.1109/ICSENS.2017.8234023 N1 - IEEE Catalog Numer: CFP17SEN-ART PB - IEEE CY - Piscataway, NJ ER - TY - CHAP A1 - Tschöpe, Constanze A1 - Duckhorn, Frank A1 - Richter, Christian A1 - Blüthgen, Peter A1 - Wolff, Matthias T1 - An embedded system for acoustic pattern recognition T2 - IEEE SENSORS Proceedings, Glasgow, Scotland, UK, Oct. 29 - Nov. 1, 2017 Y1 - 2017 SN - 978-1-5090-1012-7 U6 - https://doi.org/10.1109/ICSENS.2017.8234380 N1 - IEEE Catalog Numer: CFP17SEN-ART PB - IEEE CY - Piscataway, NJ ER - TY - GEN A1 - Herke, Max A1 - Reuter, Marvin A1 - Mayer, A. A1 - Spallek, Jacob A1 - Rattay, Petra A1 - Moor, Irene A1 - Richter, Matthias T1 - Wie wirkt sich die sozioökonomische Komposition der Schule auf Ungleichheiten im subjektiven Wohlbefinden von Schülerinnen und Schülern in Deutschland aus? T2 - Gesundheitswesen N2 - Einleitung Zielsetzung des Beitrags ist es, zu untersuchen, inwiefern die sozioökonomische Komposition von Schulen mit dem Wohlbefinden von Schülerinnen und Schülern 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 Schülern der Sekundarstufe I untersucht. Methoden Es wurden Daten der Startkohorte „Klasse 5“ des Nationalen Bildungspanels (NEPS) herangezogen. Die Kohorte startete 2010 mit einer repräsentativen Stichprobe von Fünftklässlern in Deutschland, welche jährlich nachverfolgt wurden. Es wurden Erhebungswellen von der fünften bis zur neunten Klasse zusammengefasst. Damit konnten 14.265 Beobachtungen mit vollständigen Angaben von 3.977 Schülerinnen und Schülern in 218 Schulen in den Analysen berücksichtigt werden. Mit Mixed-Models wurde getestet, ob die sozioökonomische Position auf individueller und/oder schulischer Ebene und die ebenenübergreifende Interaktion dieser Indikatoren mit dem Wohlbefinden (adaptierter Personal Well-Being – School Children-Index) der Jugendlichen assoziiert ist. Es wurde für Alter, Geschlecht, Migrationshintergrund, Familienform, Schultyp und Notendurchschnitt kontrolliert. Ergebnisse Auf individueller Ebene war das elterliche Einkommen mit höherem 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 mäßig negativen Einfluss eines hohen Anteils hoch gebildeter Eltern auf das Wohlbefinden. In Sensitivitätsanalysen blieben diese Zusammenhänge auch bei separater Betrachtung dieser Indikatoren bestehen. Die Zusammenhänge auf Individualebene wurden nicht durch die sozioökonomische Komposition von Schulen moderiert, es konnten keine signifikanten ebenenübergreifende Interaktionen festgestellt werden. Schlussfolgerung Es wurde ein Zusammenhang der sozioökonomischen Zusammensetzung der Schule mit dem subjektiven Wohlbefinden der Jugendlichen gefunden. Internationale Befunde einer Moderation der Zusammenhänge auf individueller Ebene durch sozioökonomische Charakteristika auf Schulebene konnten jedoch nicht repliziert werden. Die Zusammenhänge zwischen individueller SEP und Wohlbefinden variieren somit nicht in Abhängigkeit von der SEP auf Schulebene. Es zeigen sich vielmehr in Teilen additive Effekte für die individuelle und schulische SEP. KW - sozioökonomische Komposition KW - Schule KW - subjektives Wohlbefinden KW - Ungleichheit Y1 - 2022 UR - https://www.thieme-connect.de/products/ejournals/abstract/10.1055/s-0042-1753867 U6 - https://doi.org/10.1055/s-0042-1753867 VL - 84 IS - 08/09 SP - 826 PB - Georg Thieme Verlag ER - TY - GEN A1 - Richter, Matthias R. A1 - Cheng, Wen-Hui A1 - Crumlin, Ethan J. A1 - Drisdell, Walter S. A1 - Atwater, Harry A. A1 - Schmeißer, Dieter A1 - Lewis, Nathan S. A1 - Brunschwig, Bruce S. T1 - X‑ray Photoelectron Spectroscopy and Resonant X‑ray Spectroscopy Investigations of Interactions between Thin Metal Catalyst Films and Amorphous Titanium Dioxide Photoelectrode Protection Layers T2 - Chemistry of Materials N2 - 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. KW - X‑ray Photoelectron Spectroscopy KW - Resonant X‑ray Spectroscopy KW - titanium oxide KW - oxygen-evolution reaction KW - protection layer KW - interface interaction Y1 - 2021 U6 - https://doi.org/10.1021/acs.chemmater.0c04043 SN - 0897-4756 SN - 1520-5002 VL - 33 IS - 4 SP - 1265 EP - 1275 ER - TY - GEN A1 - Brinkert, Katharina A1 - Richter, Matthias A1 - Akay, Ömer A1 - Giersig, Michael A1 - Fountaine, Katherine T. A1 - Lewerenz, Hans-Joachim T1 - Advancing semiconductor-electrocatalyst systems: application of surface transformation films and nanosphere lithography T2 - Faraday Discussions N2 - 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. KW - shadow nanosphere lithography (SNL) KW - electrocatalyst nanostructures KW - Rh electrocatalysts KW - InP photocathodes Y1 - 2018 U6 - https://doi.org/10.1039/C8FD00003D SN - 1359-6640 SN - 1364-5498 VL - 208 SP - 523 EP - 535 ER - TY - GEN A1 - Brinkert, Katharina A1 - Richter, Matthias A1 - Akay, Ömer A1 - Liedtke, Janine A1 - Giersig, Michael A1 - Fountaine, Katherine T. A1 - Lewerenz, Hans-Joachim T1 - Efficient Solar Hydrogen Generation in Microgravity Environment T2 - Nature Communications N2 - 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. Y1 - 2018 U6 - https://doi.org/10.1038/s41467-018-04844-y SN - 2041-1723 IS - 9 ER - TY - CHAP A1 - Henkel, Karsten A1 - Kot, Małgorzata A1 - Richter, Matthias A1 - Tallarida, Massimo A1 - Schmeißer, Dieter ED - Wandelt, Klaus T1 - An (In Situ)² Approach: ALD and resPES Applied to Al₂O₃, HfO₂, and TiO₂ Ultrathin Films T2 - Encyclopedia of Interfacial Chemistry: Surface Science and Electrochemistry, Vol. 3.1 N2 - 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. KW - Atomic layer deposition (ALD) KW - Resonant photoelectron spectroscopy (resPES) KW - Band scheme KW - Partial density of states (pDOS) KW - Intrinsic charges KW - Intrinsic defects KW - Aluminum oxide (Al₂O₃) KW - Hafnium oxide (HfO₂) KW - Titanium oxide(TiO₂) Y1 - 2018 SN - 978-0-12-809739-7 SN - 978-0-12-809894-3 U6 - https://doi.org/10.1016/B978-0-12-409547-2.13852-1 SP - 18 EP - 26 PB - Elsevier CY - Oxford ER - TY - CHAP A1 - Richter, Matthias A1 - Lichterman, Michael F. A1 - Hu, Shu A1 - Crumlin, Ethan J. A1 - Axnanda, Stephanus A1 - Favaro, Marco A1 - Drisdell, Walter S. A1 - Hussain, Zahid A1 - Brunschwig, Bruce S. A1 - Liu, Zhi A1 - Lewis, Nathan S. A1 - Lewerenz, Hans-Joachim T1 - Experimental Approach for Determining Semiconductor/liquid Junction Energetics by Operando Ambient Pressure X-ray Photoelectron Spectroscopy T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - 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 KW - in operando KW - ambient pressure spectroscopy KW - water splitting Y1 - 2016 UR - http://www.dpg-verhandlungen.de/year/2016/conference/regensburg/part/o/session/72/contribution/10?lang=en SP - S. 409 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Richter, Matthias A1 - Lichterman, Michael F. A1 - Hu, Shu A1 - Crumlin, Ethan J. A1 - Axnanda, Stephanus A1 - Favaro, Marco A1 - Drisdell, Walter S. A1 - Hussain, Zahid A1 - Brunschwig, Bruce S. A1 - Liu, Zhi A1 - Lewis, Nathan S. A1 - Lewerenz, Hans-Joachim T1 - An Electrochemical, resonant Photoemission and Ambient Pressure-X-ray Photoelectron Spectroscopic Investigation of Si/TiO2/Ni/Electrolyte Interfaces T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - 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 KW - resonant photoelectron spectroscopy KW - ambient pressure spectroscopy KW - water splitting Y1 - 2016 UR - http://www.dpg-verhandlungen.de/year/2016/conference/regensburg/part/o/session/82/contribution/2?lang=en SP - S. 414 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Lichterman, Michael F. A1 - Richter, Matthias A1 - Hu, Shu A1 - Crumlin, Ethan J. A1 - Axnanda, Stephanus A1 - Favaro, Marco A1 - Drisdell, Walter S. A1 - Hussain, Zahid A1 - Brunschwig, Bruce S. A1 - Liu, Zhi A1 - Lewis, Nathan S. A1 - Lewerenz, Hans-Joachim T1 - Probing the TiO2/Liquid Interface of a Photoelectrochemical Cell by X-Ray Photoelectron Spectroscopy T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - 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 KW - X-Ray photoelectron spectroscopy KW - phototanodes KW - TiO2 passivation KW - water splitting Y1 - 2016 UR - http://www.dpg-verhandlungen.de/year/2016/conference/regensburg/part/o/session/82/contribution/1?lang=en SP - S. 414 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - GEN A1 - Schmeißer, Dieter A1 - Haeberle, Jörg A1 - Richter, Matthias A1 - Brazda, Petr T1 - Spin State and Satellite Structures of ε-Fe₂O₃ as determined by Resonant Photoelectron Spectroscopy T2 - Nuclear Instruments and Methods in Physics Research B N2 - 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. KW - Resonant photoelectron spectroscopy KW - ε-Fe2O3nano particles KW - Satellite emission Y1 - 2015 U6 - https://doi.org/10.1016/j.nimb.2015.08.062 SN - 0168-583X VL - 2015 IS - 364 SP - 127 EP - 131 ER - TY - THES A1 - Richter, Matthias T1 - Excitons and Polarons in resonant Auger decay processes N2 - 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. KW - Exciton KW - Polaron KW - X-Ray absorption spectroscopy (XAS) KW - resonant photoemission spectroscopy (resPES) KW - Auger decay Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:co1-opus-29816 UR - http://opus.kobv.de/btu/volltexte/2014/2981/ ER - TY - GEN A1 - Meyer, Werner A1 - Borislavov, Borislav A1 - Eckert, Friedrich A1 - Richter, Christian A1 - Römer, Ronald A1 - Beim Graben, Peter A1 - Huber, Markus A1 - Wolff, Matthias ED - Hillmann, Stefan ED - Weiss, Benjamin ED - Michael, Thilo ED - Möller, Sebastian T1 - Formalisierung und Implementierung einer adaptiven kognitiven Architektur unter Verwendung von Strukturdiagrammen T2 - Elektronische Sprachsignalverarbeitung 2021 : Tagungsband der 32. Konferenz Berlin, 3.-5. März 2021 N2 - Das Fachgebiet der Kognitiven Technischen Systeme zeichnet sich durch einen hohen Grad an Interdisziplinarität (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 Zusammenhängen zwischen den verschiedenen Wissensgebieten zusätzlich durch Anschaulichkeit unterstützt wird. Die vorliegende Arbeit stellt einen Fortschrittsbericht zur Realisierung eines Forschungs- und Experimentiersystems dar, mit dem wir dieses Anliegen unterstützen und über 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 repräsentationaler Datenstrukturen adaptives Verhalten auf verschiedenen Zeitskalen sowie zwei wichtige Verhaltensprogramme für das Problemlösen (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 diesjährigen Beitrag. Y1 - 2021 UR - https://www.essv.de/?year=2021 SN - 978-3-959082-27-3 SN - 0940-6832 SP - 67 EP - 76 PB - TUDpress CY - Dresden ER - TY - GEN A1 - Richter, Matthias A1 - Starke, Ulrich A1 - Schmeißer, Dieter T1 - Multiple Auger processes in Graphene T2 - Journal of Electron Spectroscopy and Related Phenomena N2 - 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. KW - Graphene KW - X-Ray absorption spectroscopy KW - XAS KW - resonant photoemission spectroscopy KW - resPES KW - multiple hole Auger Y1 - 2014 U6 - https://doi.org/10.1016/j.elspec.2013.12.009 SN - 0368-2048 IS - Vol. 192 SP - 1 EP - 6 ER - TY - GEN A1 - Richter, Matthias A1 - Friedrich, Daniel A1 - Schmeißer, Dieter T1 - Interlayer-exciton mediated three-hole-Auger-decay in the pi-band of highly oriented pyrolytic graphite T2 - Physica E N2 - 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. KW - resonant excitation KW - three hole Auger decay KW - X-ray photoelectron spectroscopy KW - HOPG Y1 - 2014 U6 - https://doi.org/10.1016/j.physe.2013.01.015 SN - 1386-9477 VL - Vol. 56 SP - 441 EP - 446 ER - TY - GEN A1 - Fischer, Christian B. A1 - Rohrbeck, Magdalena A1 - Wehner, Stefan A1 - Richter, Matthias A1 - Schmeißer, Dieter T1 - Interlayer formation of diamond-like carbon coatings on industrial polyethylene: Thickness dependent surface characterization by SEM, AFM and NEXAFS T2 - Applied Surface Science N2 - 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. KW - Diamond-like carbon KW - Interlayer formation KW - Polyethylene KW - Surface characterization KW - Coatings KW - Plastics Y1 - 2013 U6 - https://doi.org/10.1016/j.apsusc.2013.01.210 SN - 0169-4332 IS - 271 SP - 381 EP - 389 ER - TY - GEN A1 - Richter, Matthias A1 - Paloumpa, Ioanna A1 - Friedrich, Daniel A1 - Schmeißer, Dieter T1 - Multiple Auger Decay At Resonant Photo-Excitation In Carbon Thin Films T2 - ECS Transactions N2 - 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. KW - resonant photoelectron spectroscopy KW - graphene KW - HOPG KW - X-ray absorption spectroscopy (XAS) KW - X-ray photoelectron spectroscopy (XPS) Y1 - 2013 U6 - https://doi.org/10.1149/05020.0009ecst VL - 50 IS - 20 SP - 9 EP - 21 ER - TY - GEN A1 - Richter, Matthias A1 - Schmeißer, Dieter T1 - The Co2p Oxidation State In Co-PI Catalysts T2 - ECS Transactions N2 - 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. KW - X-Ray photoelectron spectroscopy (XPS) KW - X-Ray absorption spectroscopy (XAS) KW - CoPI KW - oxygene evolution KW - water oxydation Y1 - 2013 U6 - https://doi.org/10.1149/05049.0113ecst VL - 50 IS - 49 SP - 113 EP - 126 ER - TY - GEN A1 - Richter, Matthias A1 - Schmeißer, Dieter T1 - Spin states in Co-PI catalysts T2 - Applied Physics Letters N2 - 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. KW - resonant photoelectron spectroscopy KW - CoPI KW - oxygen evolution reaction Y1 - 2013 U6 - https://doi.org/10.1063/1.4811748 SN - 1077-3118 IS - 102 SP - 253904-1 EP - 253904-4 ER - TY - CHAP A1 - Richter, Matthias A1 - Schmeißer, Dieter T1 - The Co2p spin and oxidation state in Co-PI catalysts T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - 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. KW - X-Ray photoelectron spectroscopy KW - resonant photoemission spectroscopy KW - cobalt based catalyst KW - water splitting Y1 - 2013 UR - http://www.dpg-verhandlungen.de/year/2013/conference/regensburg/part/ds/session/35/contribution/9?lang=de PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - GEN A1 - Müller, Klaus A1 - Richter, Matthias A1 - Philip, Shine A1 - Kunst, Manuel A1 - Schmeißer, Dieter T1 - Excited states in P3HT and P3HT/PCBM blends T2 - BioNanoScience Y1 - 2012 SN - 2191-1630 VL - 2 IS - 1 SP - 42 EP - 51 ER - TY - GEN A1 - Richter, Matthias A1 - Friedrich, Daniel A1 - Schmeißer, Dieter T1 - Valence and Conduction band states of PCBM as probed by photoelectron spectroscopy at resonant excitation T2 - BioNanoScience Y1 - 2012 SN - 2191-1630 VL - 2 IS - 1 SP - 59 EP - 65 ER - TY - GEN A1 - Müller, Klaus A1 - Richter, Matthias A1 - Friedrich, Daniel A1 - Paloumpa, Ioanna A1 - Kramm, Ulrike Ingrid A1 - Schmeißer, Dieter T1 - Spectroscopic characterization of Cobalt–Phthalocyanine electrocatalysts for fuel cell applications T2 - Solid State Ionics N2 - 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. KW - Co-phthalocyanine KW - Catalysis KW - Oxygen reduction reaction (ORR) KW - XPS KW - NEXAFS Y1 - 2012 U6 - https://doi.org/10.1016/j.ssi.2011.12.013 SN - 1872-7689 IS - 216 SP - 78 EP - 82 ER - TY - CHAP A1 - Richter, Matthias A1 - Friedrich, Daniel A1 - Schmeißer, Dieter T1 - Multiple Auger decay at resonant photo-excitation in carbon thin films T2 - Meeting Abstracts-Electrochemical Society, Pacific Rim Meeting on Electrochemical and Solid-State Science, Honolulu, 2012 Y1 - 2012 UR - http://ma.ecsdl.org/content/MA2012-02/50/3509.full.pdf+html N1 - MA2012-02(50) SP - 3509 PB - The Electrochemical Society ER - TY - CHAP A1 - Richter, Matthias A1 - Schmeißer, Dieter T1 - The Co2p oxidation state in Co-PI catalysts T2 - Meeting Abstracts-Electrochemical Society, Pacific Rim Meeting on Electrochemical and Solid-State Science, Honolulu, 2012 Y1 - 2012 N1 - MA2012-02(14) SP - 1803 PB - The Electrochemical Society ER - TY - CHAP A1 - Schmeißer, Dieter A1 - Richter, Matthias A1 - Tallarida, Massimo ED - Heber, Jörg ED - Schlom, Darrell ED - Tokura, Yoshinori ED - Waser, Rainer ED - Wuttig, Matthias T1 - Intrinsic defects in TiO2 to explain resistive switching devices T2 - Frontiers in Electronic Materials: A Collection of Extended Abstracts of the Nature Conference Frontiers in Electronic Materials, June 17 to 20 2012, Aachen, Germany KW - resonant photoelectron spectroscopy KW - Auger processes KW - XPS KW - X-ray absorption spectroscopy Y1 - 2012 SN - 978-3-527-41191-7 U6 - https://doi.org/10.1002/9783527667703.ch45 SP - 255 EP - 256 PB - Wiley-VCH CY - Weinheim ER - TY - CHAP A1 - Philip, Shine A1 - Müller, Klaus A1 - Richter, Matthias A1 - Kunst, Marinus A1 - Schmeißer, Dieter T1 - Study of excited states and a model for exciton-polaron interaction in P3HT T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 47 N2 - 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. Y1 - 2012 UR - http://www.dpg-verhandlungen.de/year/2012/conference/berlin/part/ds/session/44/contribution/31 SN - 0420-0195 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Rohrbeck, Magdalena A1 - Fischer, Christian B. A1 - Wehner, Stefan A1 - Richter, Matthias A1 - Schmeißer, Dieter T1 - Diamond-Like Carbon Coatings on Industrial Polyethylene Surfaces T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 47 N2 - 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. Y1 - 2012 UR - http://www.dpg-verhandlungen.de/year/2012/conference/berlin/part/o/session/35/contribution/28 SN - 0420-0195 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Richter, Matthias A1 - Friedrich, Daniel A1 - Schmeißer, Dieter T1 - 3h-Auger decay in the π-band of HOPG T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 47 N2 - 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. Y1 - 2012 UR - http://www.dpg-verhandlungen.de/year/2012/conference/berlin/part/ds/session/35/contribution/4 SN - 0420-0195 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Fischer, Christian B. A1 - Rohrbeck, Magdalena A1 - Wehner, Stefan A1 - Richter, Matthias A1 - Schmeißer, Dieter T1 - Diamond-Like Carbon Coatings on Selected Plastic Materials T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 47 N2 - 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. Y1 - 2012 UR - http://www.dpg-verhandlungen.de/year/2012/conference/berlin/part/o/session/66/contribution/9 SN - 0420-0195 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Richter, Matthias A1 - Schmeißer, Dieter T1 - Electronic structure and optical properties of P3HT - Evidence of 2D-polarons in P3HT T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 46 N2 - 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 Y1 - 2011 UR - http://www.dpg-verhandlungen.de/year/2011/conference/dresden/part/ds/session/64/contribution/3 SN - 0420-0195 SP - S. 311 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Mbua, Roy A1 - Müller, Klaus A1 - Richter, Matthias A1 - Henkel, Karsten A1 - Paloumpa, Ioanna A1 - Schmeißer, Dieter A1 - Kramm, Ulricke T1 - Investigation of new Catalysts for PEM Fuel Cells T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 46 N2 - 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. Y1 - 2011 UR - http://www.dpg-verhandlungen.de/year/2011/conference/dresden/part/o/session/60/contribution/119 SN - 0420-0195 SP - S. 483 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER -