TY - GEN A1 - Niskanen, Johannes A1 - Kooser, Kuno A1 - Koskelo, Jaakko A1 - Käämbre, Tanel A1 - Kunnus, Kristjan A1 - Pietzsch, Annette A1 - Quevedo, Wilson A1 - Hakala, Mikko A1 - Föhlisch, Alexander A1 - Huotari, Simo A1 - Kukk, Edwin T1 - Density functional simulation of resonant inelastic X-ray scattering experiments in liquids: acetonitrile N2 - In this paper we report an experimental and computational study of liquid acetonitrile (H3C–C[triple bond, length as m-dash]N) by resonant inelastic X-ray scattering (RIXS) at the N K-edge. The experimental spectra exhibit clear signatures of the electronic structure of the valence states at the N site and incident-beam-polarization dependence is observed as well. Moreover, we find fine structure in the quasielastic line that is assigned to finite scattering duration and nuclear relaxation. We present a simple and light-to-evaluate model for the RIXS maps and analyze the experimental data using this model combined with ab initio molecular dynamics simulations. In addition to polarization-dependence and scattering-duration effects, we pinpoint the effects of different types of chemical bonding to the RIXS spectrum and conclude that the H2C–C[double bond, length as m-dash]NH isomer, suggested in the literature, does not exist in detectable quantities. We study solution effects on the scattering spectra with simulations in liquid and in vacuum. The presented model for RIXS proved to be light enough to allow phase-space-sampling and still accurate enough for identification of transition lines in physical chemistry research by RIXS. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 331 Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-395133 ER - TY - JOUR A1 - Schreck, Simon A1 - Pietzsch, Annette A1 - Kennedy, Brian A1 - Sathe, Conny A1 - Miedema, Piter S. A1 - Techert, Simone A1 - Strocov, Vladimir N. A1 - Schmitt, Thorsten A1 - Hennies, Franz A1 - Rubensson, Jan-Erik A1 - Föhlisch, Alexander T1 - Ground state potential energy surfaces around selected atoms from resonant inelastic x-ray scattering JF - Scientific reports N2 - Thermally driven chemistry as well as materials’ functionality are determined by the potential energy surface of a systems electronic ground state. This makes the potential energy surface a central and powerful concept in physics, chemistry and materials science. However, direct experimental access to the potential energy surface locally around atomic centers and to its long-range structure are lacking. Here we demonstrate how sub-natural linewidth resonant inelastic soft x-ray scattering at vibrational resolution is utilized to determine ground state potential energy surfaces locally and detect long-range changes of the potentials that are driven by local modifications. We show how the general concept is applicable not only to small isolated molecules such as O2 but also to strongly interacting systems such as the hydrogen bond network in liquid water. The weak perturbation to the potential energy surface through hydrogen bonding is observed as a trend towards softening of the ground state potential around the coordinating atom. The instrumental developments in high resolution resonant inelastic soft x-ray scattering are currently accelerating and will enable broad application of the presented approach. With this multidimensional potential energy surfaces that characterize collective phenomena such as (bio)molecular function or high-temperature superconductivity will become accessible in near future. Y1 - 2016 U6 - https://doi.org/10.1038/srep20054 SN - 2045-2322 VL - 6 PB - Nature Publ. Group CY - London ER - TY - JOUR A1 - Eckert, Sebastian A1 - Miedema, P. S. A1 - Quevedo, W. A1 - Fondell, Mattis A1 - Beye, Martin A1 - Pietzsch, Annette A1 - Ross, M. A1 - Khalil, M. A1 - Föhlisch, Alexander T1 - Molecular structures and protonation state of 2-Mercaptopyridine in aqueous solution JF - Chemical physics letters N2 - The speciation of 2-Mercaptopyridine in aqueous solution has been investigated with nitrogen 1s Near Edge X-ray Absorption Fine Structure spectroscopy and time dependent Density Functional Theory. The prevalence of distinct species as a function of the solvent basicity is established. No indications of dimerization towards high concentrations are found. The determination of different molecular structures of 2-Mercaptopyridine in aqueous solution is put into the context of proton-transfer in keto-enol and thione-thiol tautomerisms. (C) 2016 The Authors. Published by Elsevier B.V. Y1 - 2016 U6 - https://doi.org/10.1016/j.cplett.2016.01.050 SN - 0009-2614 SN - 1873-4448 VL - 647 SP - 103 EP - 106 PB - Elsevier CY - Amsterdam ER - TY - GEN A1 - Eckert, Sebastian A1 - Miedema, Piter A1 - Quevedo, Wilson A1 - O'Cinneide, B. A1 - Fondell, Mattis A1 - Beye, Martin A1 - Pietzsch, Annette A1 - Ross, Matthew R. A1 - Khalil, Munira A1 - Föhlisch, Alexander T1 - Molecular structures and protonation state of 2-Mercaptopyridine in aqueous solution T2 - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - The speciation of 2-Mercaptopyridine in aqueous solution has been investigated with nitrogen 1s Near Edge X-ray Absorption Fine Structure spectroscopy and time dependent Density Functional Theory. The prevalence of distinct species as a function of the solvent basicity is established. No indications of dimerization towards high concentrations are found. The determination of different molecular structures of 2-Mercaptopyridine in aqueous solution is put into the context of proton-transfer in keto-enol and thione-thiol tautomerisms. (C) 2016 The Authors. Published by Elsevier B.V. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 953 KW - ray-emission-spectroscopy KW - x-ray KW - hydroxypyridine-pyridone KW - protomeric equilibria KW - self-association KW - CU(110) KW - valence Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-437473 SN - 1866-8372 IS - 953 SP - 103 EP - 106 ER -