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 - Niskanen, Johannes A1 - Fondell, Mattis A1 - Sahle, Christoph J. A1 - Eckert, Sebastian A1 - Jay, Raphael Martin A1 - Gilmore, Keith A1 - Pietzsch, Annette A1 - Dantz, Marcus A1 - Lu, Xingye A1 - McNally, Daniel E. A1 - Schmitt, Thorsten A1 - Vaz da Cruz, Vinicius A1 - Kimberg, Victor A1 - Föhlisch, Alexander A1 - Gel’mukhanov, Faris T1 - Compatibility of quantitative X-ray spectroscopy with continuous distribution models of water at ambient conditions JF - Proceedings of the National Academy of Sciences of the United States of America N2 - The phase diagram of water harbors controversial views on underlying structural properties of its constituting molecular moieties, its fluctuating hydrogen-bonding network, as well as pair-correlation functions. In this work, long energy-range detection of the X-ray absorption allows us to unambiguously calibrate the spectra for water gas, liquid, and ice by the experimental atomic ionization cross-section. In liquid water, we extract the mean value of 1.74 +/- 2.1% donated and accepted hydrogen bonds per molecule, pointing to a continuous-distribution model. In addition, resonant inelastic X-ray scattering with unprecedented energy resolution also supports continuous distribution of molecular neighborhoods within liquid water, as do X-ray emission spectra once the femtosecond scattering duration and proton dynamics in resonant X-ray-matter interaction are taken into account. Thus, X-ray spectra of liquid water in ambient conditions can be understood without a two-structure model, whereas the occurrence of nanoscale-length correlations within the continuous distribution remains open. KW - structure of water KW - X-ray spectroscopy KW - continuous distribution model Y1 - 2019 U6 - https://doi.org/10.1073/pnas.1815701116 SN - 0027-8424 VL - 116 IS - 10 SP - 4058 EP - 4063 PB - National Acad. of Sciences CY - Washington ER - TY - JOUR A1 - Jay, Raphael Martin A1 - Eckert, Sebastian A1 - Vaz da Cruz, Vinicius A1 - Fondell, Mattis A1 - Mitzner, Rolf A1 - Föhlisch, Alexander T1 - Covalency-driven preservation of local charge densities in a metal-to-ligand charge-transfer excited iron photosensitizer JF - Angewandte Chemie : a journal of the Gesellschaft Deutscher Chemiker ; International edition N2 - Charge-density rearrangements after metal-to-ligand charge-transfer excitation in an iron photosensitizer are investigated by R. M Jay, A. Fohlisch et al. in their Communication (DOI: 10.1002/anie.201904761). By using time-resolved X-ray absorption spectroscopy, surprising covalency-effects are revealed that inhibit charge-separation at the intra-molecular level. Furthermore, the underlying mechanism is proposed to be generally in effect for all commonly used photosensitizers in light-harvesting applications, which challenges the common perception of electronic charge-transfer. KW - charge-transfer KW - density functional calculations KW - iron KW - photochemistry KW - X-ray absorption spectroscopy Y1 - 2019 U6 - https://doi.org/10.1002/anie.201904761 SN - 1433-7851 SN - 1521-3773 VL - 58 IS - 31 SP - 10742 EP - 10746 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Pietzsch, Annette A1 - Niskanen, Johannes A1 - Vaz da Cruz, Vinicius A1 - Büchner, Robby A1 - Eckert, Sebastian A1 - Fondell, Mattis A1 - Jay, Raphael Martin A1 - Lu, Xingye A1 - McNally, Daniel A1 - Schmitt, Thorsten A1 - Föhlisch, Alexander T1 - Cuts through the manifold of molecular H2O potential energy surfaces in liquid water at ambient conditions JF - Proceedings of the National Academy of Sciences of the United States of America N2 - The fluctuating hydrogen bridge bonded network of liquid water at ambient conditions entails a varied ensemble of the underlying constituting H2O molecular moieties. This is mirrored in a manifold of the H2O molecular potentials. Subnatural line width resonant inelastic X-ray scattering allowed us to quantify the manifold of molecular potential energy surfaces along the H2O symmetric normal mode and the local asymmetric O-H bond coordinate up to 1 and 1.5 angstrom, respectively. The comparison of the single H2O molecular potentials and spectroscopic signatures with the ambient conditions liquid phase H2O molecular potentials is done on various levels. In the gas phase, first principles, Morse potentials, and stepwise harmonic potential reconstruction have been employed and benchmarked. In the liquid phase the determination of the potential energy manifold along the local asymmetric O-H bond coordinate from resonant inelastic X-ray scattering via the bound state oxygen ls to 4a(1) resonance is treated within these frameworks. The potential energy surface manifold along the symmetric stretch from resonant inelastic X-ray scattering via the oxygen 1 s to 2b(2) resonance is based on stepwise harmonic reconstruction. We find in liquid water at ambient conditions H2O molecular potentials ranging from the weak interaction limit to strongly distorted potentials which are put into perspective to established parameters, i.e., intermolecular O-H, H-H, and O-O correlation lengths from neutron scattering. KW - water KW - potential ene rgy surface KW - RIXS Y1 - 2022 U6 - https://doi.org/10.1073/pnas.2118101119 SN - 1091-6490 VL - 119 IS - 28 PB - National Acad. of Sciences CY - Washington, DC ER - TY - JOUR A1 - Eckert, Sebastian A1 - Mascarenhas, Eric Johnn A1 - Mitzner, Rolf A1 - Jay, Raphael Martin A1 - Pietzsch, Annette A1 - Fondell, Mattis A1 - Vaz da Cruz, Vinicius A1 - Föhlisch, Alexander T1 - From the free ligand to the transition metal complex BT - FeEDTA(-) formation seen at ligand K-Edges JF - Inorganic chemistry N2 - Chelating agents are an integral part of transition metal complex chemistry with broad biological and industrial relevance. The hexadentate chelating agent ethylenediaminetetraacetic acid (EDTA) has the capability to bind to metal ions at its two nitrogen and four of its carboxylate oxygen sites. We use resonant inelastic X-ray scattering at the 1s absorption edge of the aforementioned elements in EDTA and the iron(III)-EDTA complex to investigate the impact of the metal-ligand bond formation on the electronic structure of EDTA. Frontier orbital distortions, occupation changes, and energy shifts through metal- ligand bond formation are probed through distinct spectroscopic signatures. KW - Energy KW - Ligands KW - Metals KW - Nitrogen KW - Oxygen Y1 - 2022 U6 - https://doi.org/10.1021/acs.inorgchem.2c00789 SN - 0020-1669 SN - 1520-510X VL - 61 IS - 27 SP - 10321 EP - 10328 PB - American Chemical Society CY - Washington 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 - 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 - Jay, Raphael M. A1 - Vaz da Cruz, Vinicius A1 - Eckert, Sebastian A1 - Fondell, Mattis A1 - Mitzner, Rolf A1 - Föhlisch, Alexander T1 - Probing solute-solvent interactions of transition metal complexes using L-edge absorption spectroscopy JF - The journal of physical chemistry : B, Condensed matter, materials, surfaces, interfaces & biophysical chemistry N2 - In order to tailor solution-phase chemical reactions involving transition metal complexes, it is critical to understand how their valence electronic charge distributions are affected by the solution environment. Here, solute-solvent interactions of a solvatochromic mixed-ligand iron complex were investigated using X-ray absorption spectroscopy at the transition metal L-2,L-3-edge. Due to the selectivity of the corresponding core excitations to the iron 3d orbitals, the method grants direct access to the valence electronic structure around the iron center and its response to interactions with the solvent environment. A linear increase of the total L-2,L-3-edge absorption cross section as a function of the solvent Lewis acidity is revealed. The effect is caused by relative changes in different metal-ligand-bonding channels, which preserve local charge densities while increasing the density of unoccupied states around the iron center. These conclusions are corroborated by a combination of molecular dynamics and spectrum simulations based on time-dependent density functional theory. The simulations reproduce the spectral trends observed in the X-ray but also optical absorption experiments. Our results underscore the importance of solute-solvent interactions when aiming for an accurate description of the valence electronic structure of solvated transition metal complexes and demonstrate how L-2,L-3-edge absorption spectroscopy can aid in understanding the impact of the solution environment on intramolecular covalency and the electronic charge distribution. KW - basis-sets KW - charge-transfer KW - density KW - dynamics KW - electron localization KW - iron KW - solvation KW - spin-crossover KW - tranfer excited-state KW - x-ray-absorption Y1 - 2020 U6 - https://doi.org/10.1021/acs.jpcb.0c00638 SN - 1520-6106 SN - 1520-5207 VL - 124 IS - 27 SP - 5636 EP - 5645 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Ochmann, Miguel A1 - Vaz da Cruz, Vinicius A1 - Eckert, Sebastian A1 - Huse, Nils A1 - Föhlisch, Alexander T1 - R-Group stabilization in methylated formamides observed by resonant inelastic X-ray scattering JF - Chemical communications: ChemComm N2 - The inherent stability of methylated formamides is traced to a stabilization of the deep-lying sigma-framework by resonant inelastic X-ray scattering at the nitrogen K-edge. Charge transfer from the amide nitrogen to the methyl groups underlie this stabilization mechanism that leaves the aldehyde group essentially unaltered and explains the stability of secondary and tertiary amides. Y1 - 2022 U6 - https://doi.org/10.1039/d2cc00053a SN - 1359-7345 SN - 1364-548X VL - 58 IS - 63 SP - 8834 EP - 8837 PB - The Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Liu, Ji-Cai A1 - Vaz da Cruz, Vinicius A1 - Polyutov, Sergey A1 - Föhlisch, Alexander T1 - Recoil-induced dissociation in hard-x-ray photoionization JF - Physical review : A, Atomic, molecular, and optical physics N2 - We predict the recoil-induced molecular dissociation in hard-x-ray photoionization. The recoil effect is caused by electronic and photon momentum exchange with the molecule. We show the strong role of relativistic effects for the studied molecular fragmentation. The recoil-induced fragmentation of the molecule is caused by elongation of the bond due to the vibrational recoil effect and because of the centrifugal force caused by the rotational recoil. The calculations of the x-ray photoelectron spectra of the H-2 and NO molecules show that the predicted effects can be observed in high-energy synchrotrons like SOLEIL, SPring-8, PETRA, and XFEL SACLA. The relativistic effect enhances the recoil momentum transfer and makes it strongly sensitive to the direction of ejection of the fast photoelectron with respect to the photon momentum. Y1 - 2019 U6 - https://doi.org/10.1103/PhysRevA.100.053408 SN - 2469-9926 SN - 2469-9934 VL - 100 IS - 5 PB - American Physical Society CY - College Park ER - TY - JOUR A1 - Vaz da Cruz, Vinicius A1 - Büchner, Robby A1 - Fondell, Mattis A1 - Pietzsch, Annette A1 - Eckert, Sebastian A1 - Föhlisch, Alexander T1 - Targeting individual tautomers in equilibrium by resonant inelastic X-ray scattering JF - The journal of physical chemistry letters N2 - Tautomerism is one of the most important forms of isomerism, owing to the facile interconversion between species and the large differences in chemical properties introduced by the proton transfer connecting the tautomers. Spectroscopic techniques are often used for the characterization of tautomers. In this context, separating the overlapping spectral response of coexisting tautomers is a long-standing challenge in chemistry. Here, we demonstrate that by using resonant inelastic X-ray scattering tuned to the core excited states at the site of proton exchange between tautomers one is able to experimentally disentangle the manifold of valence excited states of each tautomer in a mixture. The technique is applied to the prototypical keto-enol equilibrium of 3-hydroxypyridine in aqueous solution. We detect transitions from the occupied orbitals into the LUMO for each tautomer in solution, which report on intrinsic and hydrogen-bond-induced orbital polarization within the pi and sigma manifolds at the proton-transfer site. KW - Equilibrium KW - Molecular structure KW - Molecules KW - Nitrogen KW - Solvents Y1 - 2022 U6 - https://doi.org/10.1021/acs.jpclett.1c03453 SN - 1948-7185 VL - 13 IS - 10 SP - 2459 EP - 2466 PB - American Chemical Society CY - Washington 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 -