@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 = {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{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} }