TY - JOUR A1 - Couto, Rafael C. A1 - Cruz, Vinicius V. A1 - Ertan, Emelie A1 - Eckert, Sebastian A1 - Fondell, Mattis A1 - Dantz, Marcus A1 - Kennedy, Brian A1 - Schmitt, Thorsten A1 - Pietzsch, Annette A1 - Guimaraes, Freddy F. A1 - Agren, Hans A1 - Odelius, Michael A1 - Kimberg, Victor A1 - Föhlisch, Alexander T1 - Selective gating to vibrational modes through resonant X-ray scattering JF - Nature Communications N2 - The dynamics of fragmentation and vibration of molecular systems with a large number of coupled degrees of freedom are key aspects for understanding chemical reactivity and properties. Here we present a resonant inelastic X-ray scattering (RIXS) study to show how it is possible to break down such a complex multidimensional problem into elementary components. Local multimode nuclear wave packets created by X-ray excitation to different core-excited potential energy surfaces (PESs) will act as spatial gates to selectively probe the particular ground-state vibrational modes and, hence, the PES along these modes. We demonstrate this principle by combining ultra-high resolution RIXS measurements for gas-phase water with state-of-the-art simulations. Y1 - 2017 U6 - https://doi.org/10.1038/ncomms14165 SN - 2041-1723 VL - 8 PB - Nature Publ. Group CY - London ER - TY - JOUR A1 - Eckert, Sebastian A1 - Vaz da Cruz, Vinicius A1 - Ertan, Emelie A1 - Ignatova, Nina A1 - Polyutov, Sergey A1 - Couto, Rafael C. A1 - Fondell, Mattis A1 - Dantz, Marcus A1 - Kennedy, Brian A1 - Schmitt, Thorsten A1 - Pietzsch, Annette A1 - Odelius, Michael A1 - Föhlisch, Alexander T1 - One-dimensional cuts through multidimensional potential-energy surfaces by tunable x rays JF - Physical review : A, Atomic, molecular, and optical physics N2 - The concept of the potential-energy surface (PES) and directional reaction coordinates is the backbone of our description of chemical reaction mechanisms. Although the eigenenergies of the nuclear Hamiltonian uniquely link a PES to its spectrum, this information is in general experimentally inaccessible in large polyatomic systems. This is due to (near) degenerate rovibrational levels across the parameter space of all degrees of freedom, which effectively forms a pseudospectrum given by the centers of gravity of groups of close-lying vibrational levels. We show here that resonant inelastic x-ray scattering (RIXS) constitutes an ideal probe for revealing one-dimensional cuts through the ground-state PES of molecular systems, even far away from the equilibrium geometry, where the independent-mode picture is broken. We strictly link the center of gravity of close-lying vibrational peaks in RIXS to a pseudospectrum which is shown to coincide with the eigenvalues of an effective one-dimensional Hamiltonian along the propagation coordinate of the core-excited wave packet. This concept, combined with directional and site selectivity of the core-excited states, allows us to experimentally extract cuts through the ground-state PES along three complementary directions for the showcase H2O molecule. Y1 - 2018 U6 - https://doi.org/10.1103/PhysRevA.97.053410 SN - 2469-9926 SN - 2469-9934 VL - 97 IS - 5 PB - American Physical Society CY - College Park ER - TY - JOUR A1 - Ertan, Emelie A1 - Savchenko, Viktoriia A1 - Ignatova, Nina A1 - Vaz da Cruz, Vinicius A1 - Couto, Rafael C. A1 - Eckert, Sebastian A1 - Fondell, Mattis A1 - Dantz, Marcus A1 - Kennedy, Brian A1 - Schmitt, Thorsten A1 - Pietzsch, Annette A1 - Föhlisch, Alexander A1 - Odelius, Michael A1 - Kimberg, Victor T1 - Ultrafast dissociation features in RIXS spectra of the water molecule JF - Physical chemistry, chemical physics : a journal of European Chemical Societies N2 - In this combined theoretical and experimental study we report on an analysis of the resonant inelastic X-ray scattering (RIXS) spectra of gas phase water via the lowest dissociative core-excited state |1s−1O4a11〉. We focus on the spectral feature near the dissociation limit of the electronic ground state. We show that the narrow atomic-like peak consists of the overlapping contribution from the RIXS channels back to the ground state and to the first valence excited state |1b−114a11〉 of the molecule. The spectral feature has signatures of ultrafast dissociation (UFD) in the core-excited state, as we show by means of ab initio calculations and time-dependent nuclear wave packet simulations. We show that the electronically elastic RIXS channel gives substantial contribution to the atomic-like resonance due to the strong bond length dependence of the magnitude and orientation of the transition dipole moment. By studying the RIXS for an excitation energy scan over the core-excited state resonance, we can understand and single out the molecular and atomic-like contributions in the decay to the lowest valence-excited state. Our study is complemented by a theoretical discussion of RIXS in the case of isotopically substituted water (HDO and D2O) where the nuclear dynamics is significantly affected by the heavier fragments' mass. Y1 - 2018 U6 - https://doi.org/10.1039/c8cp01807c SN - 1463-9076 SN - 1463-9084 VL - 20 IS - 21 SP - 14384 EP - 14397 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Jay, Raphael M. A1 - Norell, Jesper A1 - Eckert, Sebastian A1 - Hantschmann, Markus A1 - Beye, Martin A1 - Kennedy, Brian A1 - Quevedo, Wilson A1 - Schlotter, William F. A1 - Dakovski, Georgi L. A1 - Minitti, Michael P. A1 - Hoffmann, Matthias C. A1 - Mitra, Ankush A1 - Moeller, Stefan P. A1 - Nordlund, Dennis A1 - Zhang, Wenkai A1 - Liang, Huiyang W. A1 - Kunnus, Kristian A1 - Kubicek, Katharina A1 - Techert, Simone A. A1 - Lundberg, Marcus A1 - Wernet, Philippe A1 - Gaffney, Kelly A1 - Odelius, Michael A1 - Föhlisch, Alexander T1 - Disentangling Transient Charge Density and Metal-Ligand Covalency in Photoexcited Ferricyanide with Femtosecond Resonant Inelastic Soft X-ray Scattering JF - The journal of physical chemistry letters N2 - Soft X-ray spectroscopies are ideal probes of the local valence electronic structure of photocatalytically active metal sites. Here, we apply the selectivity of time resolved resonant inelastic X-ray scattering at the iron L-edge to the transient charge distribution of an optically excited charge-transfer state in aqueous ferricyanide. Through comparison to steady-state spectra and quantum chemical calculations, the coupled effects of valence-shell closing and ligand-hole creation are experimentally and theoretically disentangled and described in terms of orbital occupancy, metal-ligand covalency, and ligand field splitting, thereby extending established steady-state concepts to the excited-state domain. pi-Back-donation is found to be mainly determined by the metal site occupation, whereas the ligand hole instead influences sigma-donation. Our results demonstrate how ultrafast resonant inelastic X-ray scattering can help characterize local charge distributions around catalytic metal centers in short-lived charge-transfer excited states, as a step toward future rationalization and tailoring of photocatalytic capabilities of transition-metal complexes. Y1 - 2018 U6 - https://doi.org/10.1021/acs.jpclett.8b01429 SN - 1948-7185 VL - 9 IS - 12 SP - 3538 EP - 3543 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Leitner, T. A1 - Josefsson, Ida A1 - Mazza, T. A1 - Miedema, Piter S. A1 - Schröder, H. A1 - Beye, Martin A1 - Kunnus, Kristjan A1 - Schreck, S. A1 - Düsterer, Stefan A1 - Föhlisch, Alexander A1 - Meyer, M. A1 - Odelius, Michael A1 - Wernet, Philippe T1 - Time-resolved electron spectroscopy for chemical analysis of photodissociation BT - Photoelectron spectra of Fe(CO)(5), Fe(CO)(4), and Fe(CO)(3) JF - The journal of chemical physics : bridges a gap between journals of physics and journals of chemistr N2 - The prototypical photoinduced dissociation of Fe(CO)(5) in the gas phase is used to test time-resolved x-ray photoelectron spectroscopy for studying photochemical reactions. Upon one-photon excitation at 266 nm, Fe(CO)(5) successively dissociates to Fe(CO)(4) and Fe(CO)(3) along a pathway where both fragments retain the singlet multiplicity of Fe(CO)(5). The x-ray free-electron laser FLASH is used to probe the reaction intermediates Fe(CO)(4) and Fe(CO)(3) with time-resolved valence and core-level photoelectron spectroscopy, and experimental results are interpreted with ab initio quantum chemical calculations. Changes in the valence photoelectron spectra are shown to reflect changes in the valenceorbital interactions upon Fe-CO dissociation, thereby validating fundamental theoretical concepts in Fe-CO bonding. Chemical shifts of CO 3 sigma inner-valence and Fe 3 sigma core-level binding energies are shown to correlate with changes in the coordination number of the Fe center. We interpret this with coordination-dependent charge localization and core-hole screening based on calculated changes in electron densities upon core-hole creation in the final ionic states. This extends the established capabilities of steady-state electron spectroscopy for chemical analysis to time-resolved investigations. It could also serve as a benchmark for howcharge and spin density changes in molecular dissociation and excited-state dynamics are expressed in valence and core-level photoelectron spectroscopy. Published by AIP Publishing. Y1 - 2018 U6 - https://doi.org/10.1063/1.5035149 SN - 0021-9606 SN - 1089-7690 VL - 149 IS - 4 PB - American Institute of Physics CY - Melville ER - TY - JOUR A1 - Eckert, Sebastian A1 - Norell, Jesper A1 - Jay, Raphael Martin A1 - Fondell, Mattis A1 - Mitzner, Rolf A1 - Odelius, Michael A1 - Föhlisch, Alexander T1 - T-1 Population as the Driver of Excited-State Proton-Transfer in 2-Thiopyridone JF - Chemistry - a European journal N2 - Excited-state proton transfer (ESPT) is a fundamental process in biomolecular photochemistry, but its underlying mediators often evade direct observation. We identify a distinct pathway for ESPT in aqueous 2-thiopyridone, by employing transient N1s X-ray absorption spectroscopy and multi-configurational spectrum simulations. Photoexcitations to the singlet S-2 and S-4 states both relax promptly through intersystem crossing to the triplet T-1 state. The T-1 state, through its rapid population and near nanosecond lifetime, mediates nitrogen site deprotonation by ESPT in a secondary intersystem crossing to the S-0 potential energy surface. This conclusively establishes a dominant ESPT pathway for the system in aqueous solution, which is also compatible with previous measurements in acetonitrile. Thereby, the hitherto open questions of the pathway for ESPT in the compound, including its possible dependence on excitation wavelength and choice of solvent, are resolved. KW - excited-state proton-transfer KW - intersystem crossing KW - nitrogen KW - photochemistry KW - X-ray absorption Y1 - 2019 U6 - https://doi.org/10.1002/chem.201804166 SN - 0947-6539 SN - 1521-3765 VL - 25 IS - 7 SP - 1733 EP - 1739 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Vaz da Cruz, Vinicius A1 - Eckert, Sebastian A1 - Iannuzzi, Marcella A1 - Ertan, Emelie A1 - Pietzsch, Annette A1 - Couto, Rafael C. A1 - Niskanen, Johannes A1 - Fondell, Mattis A1 - Dantz, Marcus A1 - Schmitt, Thorsten A1 - Lu, Xingye A1 - McNally, Daniel A1 - Jay, Raphael Martin A1 - Kimberg, Victor A1 - Föhlisch, Alexander A1 - Odelius, Michael T1 - Probing hydrogen bond strength in liquid water by resonant inelastic X-ray scattering JF - Nature Communications N2 - Local probes of the electronic ground state are essential for understanding hydrogen bonding in aqueous environments. When tuned to the dissociative core-excited state at the O1s pre-edge of water, resonant inelastic X-ray scattering back to the electronic ground state exhibits a long vibrational progression due to ultrafast nuclear dynamics. We show how the coherent evolution of the OH bonds around the core-excited oxygen provides access to high vibrational levels in liquid water. The OH bonds stretch into the long-range part of the potential energy curve, which makes the X-ray probe more sensitive than infra-red spectroscopy to the local environment. We exploit this property to effectively probe hydrogen bond strength via the distribution of intramolecular OH potentials derived from measurements. In contrast, the dynamical splitting in the spectral feature of the lowest valence-excited state arises from the short-range part of the OH potential curve and is rather insensitive to hydrogen bonding. Y1 - 2019 U6 - https://doi.org/10.1038/s41467-019-08979-4 SN - 2041-1723 VL - 10 PB - Nature Publ. Group CY - London ER - TY - JOUR A1 - Eckert, Sebastian A1 - Norell, Jesper A1 - Miedema, Piter S. A1 - Beye, Martin A1 - Fondell, Mattis A1 - Quevedo, Wilson A1 - Kennedy, Brian A1 - Hantschmann, Markus A1 - Pietzsch, Annette A1 - van Kuiken, Benjamin A1 - Ross, Matthew A1 - Minitti, Michael P. A1 - Moeller, Stefan P. A1 - Schlotter, William F. A1 - Khalil, Munira A1 - Odelius, Michael A1 - Föhlisch, Alexander T1 - Untersuchung unabhängiger N‐H‐ und N‐C‐Bindungsverformungen auf ultrakurzen Zeitskalen mit resonanter inelastischer Röntgenstreuung JF - Angewandte Chemie N2 - Die Femtosekundendynamik nach resonanten Photoanregungen mit optischen und Röntgenpulsen ermöglicht eine selektive Verformung von chemischen N‐H‐ und N‐C‐Bindungen in 2‐Thiopyridon in wässriger Lösung. Die Untersuchung der orbitalspezifischen elektronischen Struktur und ihrer Dynamik auf ultrakurzen Zeitskalen mit resonanter inelastischer Röntgenstreuung an der N1s‐Resonanz am Synchrotron und dem Freie‐Elektronen‐Laser LCLS in Kombination mit quantenchemischen Multikonfigurationsberechnungen erbringen den direkten Nachweis dieser kontrollierten photoinduzierten Molekülverformungen und ihrer ultrakurzen Zeitskala. KW - Photochemie KW - Protonierung KW - RIXS (resonante inelastische Röntgenstreuung) KW - Selektiver Bindungsbruch KW - Stickstoff Y1 - 2017 U6 - https://doi.org/10.1002/ange.201700239 SN - 1521-3757 SN - 1521-3773 VL - 129 IS - 22 SP - 6184 EP - 6188 ER - TY - JOUR A1 - Vaz da Cruz, Vinícius A1 - Ignatova, Nina A1 - Couto, Rafael A1 - Fedotov, Daniil A1 - Rehn, Dirk R. A1 - Savchenko, Viktoriia A1 - Norman, Patrick A1 - Ågren, Hans A1 - Polyutov, Sergey A1 - Niskanen, Johannes A1 - Eckert, Sebastian A1 - Jay, Raphael Martin A1 - Fondell, Mattis A1 - Schmitt, Thorsten A1 - Pietzsch, Annette A1 - Föhlisch, Alexander A1 - Odelius, Michael A1 - Kimberg, Victor A1 - Gel’mukhanov, Faris T1 - Nuclear dynamics in resonant inelastic X-ray scattering and X-ray absorption of methanol JF - The journal of chemical physics : bridges a gap between journals of physics and journals of chemistr N2 - We report on a combined theoretical and experimental study of core-excitation spectra of gas and liquid phase methanol as obtained with the use of X-ray absorption spectroscopy (XAS) and resonant inelastic X-ray scattering (RIXS). The electronic transitions are studied with computational methods that include strict and extended second-order algebraic diagrammatic construction [ADC(2) and ADC(2)-x], restricted active space second-order perturbation theory, and time-dependent density functional theory-providing a complete assignment of the near oxygen K-edge XAS. We show that multimode nuclear dynamics is of crucial importance for explaining the available experimental XAS and RIXS spectra. The multimode nuclear motion was considered in a recently developed "mixed representation" where dissociative states and highly excited vibrational modes are accurately treated with a time-dependent wave packet technique, while the remaining active vibrational modes are described using Franck-Condon amplitudes. Particular attention is paid to the polarization dependence of RIXS and the effects of the isotopic substitution on the RIXS profile in the case of dissociative core-excited states. Our approach predicts the splitting of the 2a RIXS peak to be due to an interplay between molecular and pseudo-atomic features arising in the course of transitions between dissociative core- and valence-excited states. The dynamical nature of the splitting of the 2a peak in RIXS of liquid methanol near pre-edge core excitation is shown. The theoretical results are in good agreement with our liquid phase measurements and gas phase experimental data available from the literature. (C) 2019 Author(s). Y1 - 2019 U6 - https://doi.org/10.1063/1.5092174 SN - 0021-9606 SN - 1089-7690 VL - 150 IS - 23 PB - American Institute of Physics CY - Melville ER - TY - JOUR A1 - Norell, Jesper A1 - Eckert, Sebastian A1 - Van Kuiken, Benjamin E. A1 - Föhlisch, Alexander A1 - Odelius, Michael T1 - Ab initio simulations of complementary K-edges and solvatization effects for detection of proton transfer in aqueous 2-thiopyridone JF - The journal of chemical physics : bridges a gap between journals of physics and journals of chemistr N2 - The nitrogen and sulfur K-edge X-ray absorption spectra of aqueous 2-thiopyridone, a model system for excited-state proton transfer in several recent time-resolved measurements, have been simulated from ab initio molecular dynamics. Spectral signatures of the local intra- and inter-molecular structure are identified and rationalized, which facilitates experimental interpretation and optimization. In particular, comparison of aqueous and gas phase spectrum simulations assesses the previously unquantified solvatization effects, where hydrogen bonding is found to yield solvatochromatic shifts up to nearly 1 eV of the main peak positions. Thereby, while each K-edge can still decisively determine the local protonation of its core-excited site, only their combined, complementary fingerprints allow separating all of the three relevant molecular forms, giving a complete picture of the proton transfer. Y1 - 2019 U6 - https://doi.org/10.1063/1.5109840 SN - 0021-9606 SN - 1089-7690 VL - 151 IS - 11 PB - American Institute of Physics CY - Melville ER -