TY - JOUR A1 - Yin, Zhong A1 - Rajkovic, Ivan A1 - Veedu, Sreevidya Thekku A1 - Deinert, Sascha A1 - Raiser, Dirk A1 - Jain, Rohit A1 - Fukuzawa, Hironobu A1 - Wada, Shin-ichi A1 - Quevedo, Wilson A1 - Kennedy, Brian A1 - Schreck, Simon A1 - Pietzsch, Annette A1 - Wernet, Philippe A1 - Ueda, Kyoshi A1 - Föhlisch, Alexander A1 - Techert, Simone T1 - Ionic solutions probed by resonant inelastic X-ray scattering JF - Zeitschrift für physikalische Chemie : international journal of research in physical chemistry and chemical physics N2 - X-ray spectroscopy is a powerful tool to study the local charge distribution of chemical systems. Together with the liquid jet it becomes possible to probe chemical systems in their natural environment, the liquid phase. In this work, we present X-ray absorption (XA), X-ray emission (XE) and resonant inelastic X-ray scattering (RIXS) data of pure water and various salt solutions and show the possibilities these methods offer to elucidate the nature of ion-water interaction. KW - X-ray Spectroscopy KW - XAS KW - XES KW - RIXS KW - Anions KW - Cations KW - Liquid Jet KW - Synchrotron Radiation Y1 - 2015 U6 - https://doi.org/10.1515/zpch-2015-0610 SN - 0942-9352 VL - 229 IS - 10-12 SP - 1855 EP - 1867 PB - De Gruyter CY - Berlin ER - TY - JOUR A1 - Wernet, Philippe A1 - Kunnus, Kristjan A1 - Josefsson, Ida A1 - Rajkovic, Ivan A1 - Quevedo, Wilson A1 - Beye, Martin A1 - Schreck, Simon A1 - Gruebel, S. A1 - Scholz, Mirko A1 - Nordlund, Dennis A1 - Zhang, Wenkai A1 - Hartsock, Robert W. A1 - Schlotter, William F. A1 - Turner, Joshua J. A1 - Kennedy, Brian A1 - Hennies, Franz A1 - de Groot, Frank M. F. A1 - Gaffney, Kelly J. A1 - Techert, Simone A1 - Odelius, Michael A1 - Föhlisch, Alexander T1 - Orbital-specific mapping of the ligand exchange dynamics of Fe(CO)(5) in solution JF - Nature : the international weekly journal of science N2 - Transition-metal complexes have long attracted interest for fundamental chemical reactivity studies and possible use in solar energy conversion(1,2). Electronic excitation, ligand loss from the metal centre, or a combination of both, creates changes in charge and spin density at the metal site(3-11) that need to be controlled to optimize complexes for photocatalytic hydrogen production(8) and selective carbon-hydrogen bond activation(9-11). An understanding at the molecular level of how transition-metal complexes catalyse reactions, and in particular of the role of the short-lived and reactive intermediate states involved, will be critical for such optimization. However, suitable methods for detailed characterization of electronic excited states have been lacking. Here we show, with the use of X-ray laser-based femtosecond-resolution spectroscopy and advanced quantum chemical theory to probe the reaction dynamics of the benchmark transition-metal complex Fe(CO)(5) in solution, that the photo-induced removal of CO generates the 16-electron Fe(CO)(4) species, a homogeneous catalyst(12,13) with an electron deficiency at the Fe centre(14,15), in a hitherto unreported excited singlet state that either converts to the triplet ground state or combines with a CO or solvent molecule to regenerate a penta-coordinated Fe species on a sub-picosecond timescale. This finding, which resolves the debate about the relative importance of different spin channels in the photochemistry of Fe(CO)(5) (refs 4, 16-20), was made possible by the ability of femtosecond X-ray spectroscopy to probe frontier-orbital interactions with atom specificity. We expect the method to be broadly applicable in the chemical sciences, and to complement approaches that probe structural dynamics in ultrafast processes. Y1 - 2015 U6 - https://doi.org/10.1038/nature14296 SN - 0028-0836 SN - 1476-4687 VL - 520 IS - 7545 SP - 78 EP - 81 PB - Nature Publ. Group CY - London ER - TY - GEN A1 - Vaz da Cruz, Vinicius A1 - Ertan, Emelie A1 - Couto, Rafael C. A1 - Eckert, Sebastian A1 - Fondell, Mattis A1 - Dantz, Marcus A1 - Kennedy, Brian A1 - Schmitt, Thorsten A1 - Pietzsch, Annette A1 - Guimarães, Freddy F. A1 - Ågren, Hans A1 - Gel'mukhanov, Faris A1 - Odelius, Michael A1 - Föhlisch, Alexander A1 - Kimberg, Victor T1 - A study of the water molecule using frequency control over nuclear dynamics in resonant X-ray scattering T2 - Postprints der Universität Potsdam Mathematisch-Naturwissenschaftliche Reihe N2 - In this combined theoretical and experimental study we report a full analysis of the resonant inelastic X-ray scattering (RIXS) spectra of H2O, D2O and HDO. We demonstrate that electronically-elastic RIXS has an inherent capability to map the potential energy surface and to perform vibrational analysis of the electronic ground state in multimode systems. We show that the control and selection of vibrational excitation can be performed by tuning the X-ray frequency across core-excited molecular bands and that this is clearly reflected in the RIXS spectra. Using high level ab initio electronic structure and quantum nuclear wave packet calculations together with high resolution RIXS measurements, we discuss in detail the mode coupling, mode localization and anharmonicity in the studied systems. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 781 KW - raman-scattering KW - vibrational structure KW - fast dissociation KW - auger spectrum KW - liquid water KW - spectroscopy KW - emission KW - collapse KW - states KW - vapor Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-436901 SN - 1866-8372 IS - 781 SP - 19573 EP - 19589 ER - TY - JOUR A1 - Vaz da Cruz, Vinicius A1 - Ertan, Emelie A1 - Couto, Rafael C. A1 - Eckert, Sebastian A1 - Fondell, Mattis A1 - Dantz, Marcus A1 - Kennedy, Brian A1 - Schmitt, Thorsten A1 - Pietzsch, Annette A1 - Guimaraes, Freddy F. A1 - Ågren, Hans A1 - Odelius, Michael A1 - Föhlisch, Alexander A1 - Kimberg, Victor T1 - A study of the water molecule using frequency control over nuclear dynamics in resonant X-ray scattering JF - Physical chemistry, chemical physics : a journal of European Chemical Societies N2 - In this combined theoretical and experimental study we report a full analysis of the resonant inelastic X-ray scattering (RIXS) spectra of H2O, D2O and HDO. We demonstrate that electronically-elastic RIXS has an inherent capability to map the potential energy surface and to perform vibrational analysis of the electronic ground state in multimode systems. We show that the control and selection of vibrational excitation can be performed by tuning the X-ray frequency across core-excited molecular bands and that this is clearly reflected in the RIXS spectra. Using high level ab initio electronic structure and quantum nuclear wave packet calculations together with high resolution RIXS measurements, we discuss in detail the mode coupling, mode localization and anharmonicity in the studied systems. Y1 - 2017 U6 - https://doi.org/10.1039/c7cp01215b SN - 1463-9076 SN - 1463-9084 VL - 19 SP - 19573 EP - 19589 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Sellberg, Jonas A. A1 - McQueen, Trevor A. A1 - Laksmono, Hartawan A1 - Schreck, Simon A1 - Beye, Martin A1 - DePonte, Daniel P. A1 - Kennedy, Brian A1 - Nordlund, Dennis A1 - Sierra, Raymond G. A1 - Schlesinger, Daniel A1 - Tokushima, Takashi A1 - Zhovtobriukh, Iurii A1 - Eckert, Sebastian A1 - Segtnan, Vegard H. A1 - Ogasawara, Hirohito A1 - Kubicek, Katharina A1 - Techert, Simone A1 - Bergmann, Uwe A1 - Dakovski, Georgi L. A1 - Schlotter, William F. A1 - Harada, Yoshihisa A1 - Bogan, Michael J. A1 - Wernet, Philippe A1 - Föhlisch, Alexander A1 - Pettersson, Lars G. M. A1 - Nilsson, Anders T1 - X-ray emission spectroscopy of bulk liquid water in "no-man's land" JF - The journal of chemical physics : bridges a gap between journals of physics and journals of chemistr N2 - The structure of bulk liquid water was recently probed by x-ray scattering below the temperature limit of homogeneous nucleation (T-H) of similar to 232 K [J. A. Sellberg et al., Nature 510, 381-384 (2014)]. Here, we utilize a similar approach to study the structure of bulk liquid water below T-H using oxygen K-edge x-ray emission spectroscopy (XES). Based on previous XES experiments [T. Tokushima et al., Chem. Phys. Lett. 460, 387-400 (2008)] at higher temperatures, we expected the ratio of the 1b(1)' and 1b(1)" peaks associated with the lone-pair orbital in water to change strongly upon deep supercooling as the coordination of the hydrogen (H-) bonds becomes tetrahedral. In contrast, we observed only minor changes in the lone-pair spectral region, challenging an interpretation in terms of two interconverting species. A number of alternative hypotheses to explain the results are put forward and discussed. Although the spectra can be explained by various contributions from these hypotheses, we here emphasize the interpretation that the line shape of each component changes dramatically when approaching lower temperatures, where, in particular, the peak assigned to the proposed disordered component would become more symmetrical as vibrational interference becomes more important. (C) 2015 AIP Publishing LLC. Y1 - 2015 U6 - https://doi.org/10.1063/1.4905603 SN - 0021-9606 SN - 1089-7690 VL - 142 IS - 4 PB - American Institute of Physics CY - Melville ER - TY - JOUR A1 - Schreck, Simon A1 - Pietzsch, Annette A1 - Kunnus, Kristjan A1 - Kennedy, Brian A1 - Quevedo, Wilson A1 - Miedema, Piter S. A1 - Wernet, Philippe A1 - Föhlisch, Alexander T1 - Dynamics of the OH group and the electronic structure of liquid alcohols JF - Structural dynamics N2 - In resonant inelastic soft x-ray scattering (RIXS) from molecular and liquid systems, the interplay of ground state structural and core-excited state dynamical contributions leads to complex spectral shapes that partially allow for ambiguous interpretations. In this work, we dissect these contributions in oxygen K-edge RIXS from liquid alcohols. We use the scattering into the electronic ground state as an accurate measure of nuclear dynamics in the intermediate core-excited state of the RIXS process. We determine the characteristic time in the core-excited state until nuclear dynamics give a measurable contribution to the RIXS spectral profiles to tau(dyn) = 1.2 +/- 0.8 fs. By detuning the excitation energy below the absorption resonance we reduce the effective scattering time below sdyn, and hence suppress these dynamical contributions to a minimum. From the corresponding RIXS spectra of liquid methanol, we retrieve the "dynamic-free" density of states and find that it is described solely by the electronic states of the free methanol molecule. From this and from the comparison of normal and deuterated methanol, we conclude that the split peak structure found in the lone-pair emission region at non-resonant excitation originates from dynamics in the O-H bond in the core-excited state. We find no evidence that this split peak feature is a signature of distinct ground state structural complexes in liquid methanol. However, we demonstrate how changes in the hydrogen bond coordination within the series of linear alcohols from methanol to hexanol affect the split peak structure in the liquid alcohols. (C) 2014 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License. Y1 - 2014 U6 - https://doi.org/10.1063/1.4897981 SN - 2329-7778 VL - 1 IS - 5 PB - American Institute of Physics CY - Melville 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 - Schreck, Simon A1 - Beye, Martin A1 - Sellberg, Jonas A. A1 - McQueen, Trevor A1 - Laksmono, Hartawan A1 - Kennedy, Brian A1 - Eckert, Sebastian A1 - Schlesinger, Daniel A1 - Nordlund, Dennis A1 - Ogasawara, Hirohito A1 - Sierra, Raymond G. A1 - Segtnan, Vegard H. A1 - Kubicek, Katharina A1 - Schlotter, William F. A1 - Dakovski, Georgi L. A1 - Moeller, Stefan P. A1 - Bergmann, Uwe A1 - Techert, Simone A1 - Pettersson, Lars G. M. A1 - Wernet, Philippe A1 - Bogan, Michael J. A1 - Harada, Yoshihisa A1 - Nilsson, Anders A1 - Föhlisch, Alexander T1 - Reabsorption of soft x-ray emission at high x-ray free-electron laserfluences JF - Physical review letters N2 - We report on oxygen K-edge soft x-ray emission spectroscopy from a liquid water jet at the Linac Coherent Light Source. We observe significant changes in the spectral content when tuning over a wide range of incident x-ray fluences. In addition the total emission yield decreases at high fluences. These modifications result from reabsorption of x-ray emission by valence-excited molecules generated by the Auger cascade. Our observations have major implications for future x-ray emission studies at intense x-ray sources. We highlight the importance of the x-ray pulse length with respect to the core-hole lifetime. Y1 - 2014 U6 - https://doi.org/10.1103/PhysRevLett.113.153002 SN - 0031-9007 SN - 1079-7114 VL - 113 IS - 15 PB - American Physical Society CY - College Park ER - TY - JOUR A1 - Rubensson, Jan-Erik A1 - Soderstrom, Johan A1 - Binggeli, Christian A1 - Grasjo, Joakim A1 - Andersson, Johan A1 - Sathe, Conny A1 - Hennies, Franz A1 - Bisogni, Valentina A1 - Huang, Yaobo A1 - Olalde, Paul A1 - Schmitt, Thorsten A1 - Strocov, Vladimir N. A1 - Föhlisch, Alexander A1 - Kennedy, Brian A1 - Pietzsch, Annette T1 - Rydberg-Resolved Resonant Inelastic Soft X-Ray Scattering: Dynamics at Core Ionization Thresholds JF - Physical review letters N2 - Resonant inelastic x-ray scattering spectra excited in the immediate vicinity of the core-level ionization thresholds of N-2 have been recorded. Final states of well-resolved symmetry-selected Rydberg series converging to valence-level ionization thresholds with vibrational excitations are observed. The results are well described by a quasi-two-step model which assumes that the excited electron is unaffected by the radiative decay. This threshold dynamics simplifies the interpretation of resonant inelastic x-ray scattering spectra considerably and facilitates characterization of low-energy excited final states in molecular systems. Y1 - 2015 U6 - https://doi.org/10.1103/PhysRevLett.114.133001 SN - 0031-9007 SN - 1079-7114 VL - 114 IS - 13 PB - American Physical Society CY - College Park ER - TY - JOUR A1 - Pietzsch, Annette A1 - Hennies, Franz A1 - Miedema, Piter S. A1 - Kennedy, Brian A1 - Schlappa, Justine A1 - Schmitt, Thorsten A1 - Strocov, Vladimir N. A1 - Föhlisch, Alexander T1 - Snapshots of the Fluctuating Hydrogen Bond Network in Liquid Water on the Sub-Femtosecond Timescale with Vibrational Resonant Inelastic x-ray Scattering JF - Physical review letters N2 - Liquid water molecules interact strongly with each other, forming a fluctuating hydrogen bond network and thereby giving rise to the anomalous phase diagram of liquid water. Consequently, symmetric and asymmetric water molecules have been found in the picosecond time average with IR and optical Raman spectroscopy. With subnatural linewidth resonant inelastic x-ray scattering (RIXS) at vibrational resolution, we take sub-femtosecond snapshots of the electronic and structural properties of water molecules in the hydrogen bond network. We derive a strong dominance of nonsymmetric molecules in liquid water in contrast to the gas phase on the sub-femtosecond timescale of RIXS and determine the fraction of highly asymmetrically distorted molecules. Y1 - 2015 U6 - https://doi.org/10.1103/PhysRevLett.114.088302 SN - 0031-9007 SN - 1079-7114 VL - 114 IS - 8 PB - American Physical Society CY - College Park ER -