TY - GEN A1 - Bär, Marcus A1 - Schubert, Björn-Arvid A1 - Marsen, Björn A1 - Wilks, Regan G. A1 - Blum, M. A1 - Krause, S. A1 - Pookpanratana, Sujitra A1 - Zhang, Y. A1 - Unold, Thomas A1 - Yang, W. A1 - Weinhardt, Lothar A1 - Heske, Clemens A1 - Schock, Hans-Werner T1 - Cu2ZnSnS4 thin-film solar cell absorbers illuminated by soft x-rays T2 - Journal of Materials Research N2 - In view of the complexity of thin-film solar cells, which are comprised of a multitude of layers, interfaces, surfaces, elements, impurities, etc., it is crucial to characterize and understand the chemical and electronic structure of these components. Because of the high complexity of the Cu2ZnSn(S,Se)4 compound semiconductor absorber material alone, this is particularly true for kesterite-based devices. Hence, this paper reviews our recent progress in the characterization of Cu2ZnSnS4 (CZTS) thin films. It is demonstrated that a combination of different soft x-ray spectroscopies is an extraordinarily powerful method for illuminating the chemical and electronic material characteristics from many different perspectives, ultimately resulting in a comprehensive picture of these properties. The focus of the article will be on secondary impurity phases, electronic structure, native oxidation, and the CZTS surface composition. Y1 - 2012 U6 - https://doi.org/10.1557/jmr.2012.59 SN - 2044-5326 VL - 27 IS - 8 SP - 1097 EP - 1104 ER - TY - GEN A1 - Weinhardt, Lothar A1 - Benkert, Andreas A1 - Meyer, Frank A1 - Blum, Monika A1 - Wilks, Regan G. A1 - Yang, Wan Li A1 - Bär, Marcus A1 - Reinert, Friedrich A1 - Heske, Clemens T1 - Nuclear dynamics and spectator effects in resonant inelastic soft x-ray scattering of gas-phase water molecules T2 - The journal of chemical physics N2 - The electronic structure of gas-phase H2O and D2O molecules has been investigated using resonant inelastic soft x-ray scattering (RIXS). We observe spectator shifts for all valence orbitals when exciting into the lowest three absorption resonances. Strong changes of the relative valence orbital emission intensities are found when exciting into the different absorption resonances, which can be related to the angular anisotropy of the RIXS process. Furthermore, excitation into the 4a1 resonance leads to nuclear dynamics on the time scale of the RIXS process; we find evidence for vibrational coupling and molecular dissociation in both, the spectator and the participant emission. Y1 - 2012 SN - 1089-7690 VL - 136 IS - 14 SP - 144311 ER - TY - GEN A1 - Blum, M. A1 - Odelius, Michael A1 - Weinhardt, Lothar A1 - Pookpanratana, Sujitra A1 - Bär, Marcus A1 - Zhang, Y. A1 - Fuchs, Oliver A1 - Yang, W. A1 - Umbach, Eberhard A1 - Heske, Clemens T1 - Ultrafast Proton Dynamics in Aqueous Amino Acid Solutions Studied by Resonant Inelastic Soft X‑ray Scattering T2 - The Journal of physical chemistry : B N2 - Resonant inelastic soft X-ray scattering (RIXS) has been used to study the electronic structure of glycine and lysine in aqueous solution. Upon variation of the pH value of the solution from acidic to basic, major changes of the nitrogen K edge RIXS data are observed for both amino acids, which are associated with the protonation and deprotonation of the amino groups. The experimental results are compared with simulations based on density functional theory, yielding a detailed understanding of the spectral changes, as well as insights into the ultrafast proton dynamics in the intermediate core-excited/ionized state of the RIXS process. Y1 - 2012 SN - 1520-5207 VL - 116 IS - 46 SP - 13757 EP - 13764 ER - TY - GEN A1 - Hofmann, Timo A1 - Yu, Ted H. A1 - Folse, Michael A1 - Weinhardt, Lothar A1 - Bär, Marcus A1 - Zhang, Yufeng A1 - Merinov, Boris V. A1 - Myers, Deborah J. A1 - Goddard, William A. A1 - Heske, Clemens T1 - Using Photoelectron Spectroscopy and Quantum Mechanics to Determine d‑Band Energies of Metals for Catalytic Applications T2 - The Journal of Physical Chemistry : C N2 - The valence band structures (VBS) of eight transition metals (Fe, Co, Ni, Cu, Pd, Ag, Pt, Au) were investigated by photoelectron spectroscopy (PES) using He I, He II, and monochromatized Al Kα excitation. The influence of final states, photoionization cross-section, and adsorption of residual gas molecules in an ultrahigh vacuum environment are discussed in terms of their impact on the VBS. We find that VBSs recorded with monochromatized Al Kα radiation are most closely comparable to the ground state density of states (DOS) derived from quantum mechanics calculations. We use the Al Kα-excited PES measurements to correct the energy scale of the calculated ground-state DOS to approximate the “true” ground-state d-band structure. Finally, we use this data to test the d-band center model commonly used to predict the electronicproperty/ catalytic-activity relationship of metals. We find that a simple continuous dependence of activity on d-band center position is not supported by our results (both experimentally and computationally). Y1 - 2012 SN - 1932-7455 VL - 116 IS - 45 SP - 24016 EP - 24026 ER -