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  - Yin, Zhong
A1  - Inhester, Ludger
A1  - Veedu, Sreevidya Thekku
A1  - Quevedo, Wilson
A1  - Pietzsch, Annette
A1  - Wernet, Philippe
A1  - Groenhof, Gerrit
A1  - Föhlisch, Alexander
A1  - Grubmueller, Helmut
A1  - Techert, Simone
T1  - Cationic and Anionic Impact on the Electronic Structure of Liquid Water
JF  - The journal of physical chemistry letters
N2  - Hydration shells around ions are crucial for many fundamental biological and chemical processes. Their local physicochemical properties are quite different from those of bulk water and hard to probe experimentally. We address this problem by combining soft X-ray spectroscopy using a liquid jet and molecular dynamics (MD) simulations together with ab initio electronic structure calculations to elucidate the water ion interaction in a MgCl2 solution at the molecular level. Our results reveal that salt ions mainly affect the electronic properties of water molecules in close vicinity and that the oxygen K-edge X-ray emission spectrum of water molecules in the first solvation shell differs significantly from that of bulk water. Ion-specific effects are identified by fingerprint features in the water X-ray emission spectra. While Mg2+ ions cause a bathochromic shift of the water lone pair orbital, the 3p orbital of the Cl- ions causes an additional peak in the water emission spectrum at around 528 eV.
Y1  - 2017
U6  - https://doi.org/10.1021/acs.jpclett.7b01392
SN  - 1948-7185
VL  - 8
SP  - 3759
EP  - 3764
PB  - American Chemical Society
CY  - Washington
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  - 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  - 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  - Liu, Chun-Yu
A1  - Ruotsalainen, Kari
A1  - Bauer, Karl
A1  - Decker, Régis
A1  - Pietzsch, Annette
A1  - Föhlisch, Alexander
T1  - Excited-state exchange interaction in NiO determined by high-resolution resonant inelastic x-ray scattering at the Ni M2,3 edges
JF  - Physical review : B, Condensed matter and materials physics
N2  - The electronic and magnetic excitations of bulk NiO have been determined using the 3A2g to 3T2g crystal-field transition at the Ni M2,3 edges with resonant inelastic x-ray scattering at 66.3- and 67.9-eV photon energies and 33-meV spectral resolution. Unambiguous assignment of the high-energy side of this state to a spin-flip satellite is achieved. We extract an effective exchange field of 89±4 meV  in the 3T2g excited final state from empirical two-peak spin-flip model. The experimental data is found consistent with crystal-field model calculations using exchange fields of 60–100 meV. Full agreement with crystal-field multiplet calculations is achieved for the incident photon energy dependence of line shapes. The lower exchange parameter in the excited state as compared to the ground-state value of 120 meV is discussed in terms of the modification of the orbital occupancy (electronic effects) and of the structural dynamics: (A) With pure electronic effects, the lower exchange energy is attributed to the reduction in effective hopping integral. (B) With no electronic effects, we use the S = 1 Heisenberg model of antiferromagnetism to derive a second-nearest-neighbor exchange constant J2 = 14.8±0.6 meV. Based on the linear correlation between J2 and the lattice parameter from pressure-dependent experiments, an upper limit of 2% local Ni-O bond elongation during the femtosecond scattering duration is derived.
Y1  - 2022
U6  - https://doi.org/10.1103/PhysRevB.106.035104
SN  - 2469-9950
SN  - 2469-9969
VL  - 106
IS  - 3
PB  - American Physical Society
CY  - Ridge, NY
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  - 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  - Büchner, Robby
A1  - Fondell, Mattis
A1  - Mascarenhas, Eric Johnn
A1  - Pietzsch, Annette
A1  - Vaz da Cruz, Vinícius
A1  - Föhlisch, Alexander
T1  - How hydrogen bonding amplifies isomeric differences in pyridones toward strong changes in acidity and tautomerism
JF  - The journal of physical chemistry : B, Condensed matter, materials, surfaces, interfaces & biophysical chemistry
N2  - Steric hindrance of hydration and hydrogen bond enhancement by localized charges have been identified as key factors for the massive chemical differences between the hydroxypyridine/pyridone isomers in aqueous solution. While all isomers occur mainly in the hydroxypyridine form in the gas phase, they differ by more than 3 orders of magnitude both in their acidity and tautomeric equilibrium constants upon hydration. By monitoring the electronic and solvation structures as a function of the protonation state and the O- substitution position on the pyridine ring, the amplification of the isomeric differences in aqueous solution has been investigated. Near-edge X-ray absorption fine structure (NEXAFS) measurements at the N K-edge served as the probe of the chemical state. The combination of molecular dynamics simulations, complete active space self-consistent field (CASSCF), and time-dependent density functional theory (TD-DFT) spectral calculations contributes to unraveling the principles of tautomerism and acidity in multiple biochemical systems based on tautomerism.
Y1  - 2021
U6  - https://doi.org/10.1021/acs.jpcb.0c10873
SN  - 1520-6106
SN  - 1520-5207
VL  - 125
IS  - 9
SP  - 2372
EP  - 2379
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Sun, Y. -P.
A1  - Miao, Q.
A1  - Pietzsch, Annette
A1  - Hennies, F.
A1  - Schmitt, T.
A1  - Strocov, V. N.
A1  - Andersson, Joakim
A1  - Kennedy, B.
A1  - Schlappa, J.
A1  - Föhlisch, Alexander
A1  - Gel&rsquo, 
A1  - mukhanov, F.
A1  - Rubensson, J. -E.
T1  - Interference between Resonant and Nonresonant Inelastic X-Ray Scattering
JF  - PHYSICAL REVIEW LETTERS
N2  - A detailed study of inelastic x-ray scattering from the ground state to the (3)Sigma(g)(3 sigma(-1)(g)3s(g)(1)) state of the O-2 molecule is presented. The observed angular anisotropy shows that the vibrational excitations within this final state are strongly dependent on the polarization of the incident radiation. The analysis demonstrates that this is a manifestation of interference between resonant and direct nonresonant inelastic x-ray scattering. This interference provides a new tool to monitor nuclear dynamics by relative rotation of the polarization vectors of the incident and scattered photons.
Y1  - 2013
U6  - https://doi.org/10.1103/PhysRevLett.110.223001
SN  - 0031-9007
VL  - 110
IS  - 22
PB  - AMER PHYSICAL SOC
CY  - COLLEGE PK
ER  - 
TY  - JOUR
A1  - Sun, Y-P
A1  - Pietzsch, Annette
A1  - Hennies, Franz
A1  - Rinkevicius, Z.
A1  - Karlsson, Hans O.
A1  - Schmitt, Thorsten
A1  - Strocov, Vladimir N.
A1  - Andersson, Joakim
A1  - Kennedy, B.
A1  - Schlappa, J.
A1  - Föhlisch, Alexander
A1  - Gel'mukhanov, F.
A1  - Rubensson, Jan-Erik
T1  - Internal symmetry and selection rules in resonant inelastic soft x-ray scattering
JF  - Journal of physics : B, Atomic, molecular and optical physics
N2  - Resonant inelastic soft x-ray scattering spectra excited at the dissociative 1 sigma(g) -> 3 sigma(u) resonance in gas-phase O(2) are presented and discussed in terms of state-of-the-art molecular theory. A new selection rule due to internal spin coupling is established, facilitating a deep analysis of the valence excited final states. Furthermore, it is found that a commonly accepted symmetry selection rule due to orbital parity breaks down, as the core hole and excited electron swap parity, thereby opening the symmetry forbidden 3 sigma(g) decay channel.
Y1  - 2011
U6  - https://doi.org/10.1088/0953-4075/44/16/161002
SN  - 0953-4075
VL  - 44
IS  - 16
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  - 
TY  - JOUR
A1  - Sun, Y. -P.
A1  - Hennies, Franz
A1  - Pietzsch, Annette
A1  - Kennedy, B.
A1  - Schmitt, Thorsten
A1  - Strocov, Vladimir N.
A1  - Andersson, Joakim
A1  - Berglund, Martin
A1  - Rubensson, Jan-Erik
A1  - Aidas, K.
A1  - Gel'mukhanov, F.
A1  - Odelius, Michael
A1  - Föhlisch, Alexander
T1  - Intramolecular soft modes and intermolecular interactions in liquid acetone
JF  - Physical review : B, Condensed matter and materials physics
N2  - Resonant inelastic x-ray scattering spectra excited at the O1s(-1)pi* resonance of liquid acetone are presented. Scattering to the electronic ground state shows a resolved vibrational progression where the dominant contribution is due to the C-O stretching mode, thus demonstrating a unique sensitivity of the method to the local potential energy surface in complex molecular systems. For scattering to electronically excited states, soft vibrational modes and, to a smaller extent, intermolecular interactions give a broadening, which blurs the vibrational fine structure. It is predicted that environmental broadening is dominant in aqueous acetone.
Y1  - 2011
U6  - https://doi.org/10.1103/PhysRevB.84.132202
SN  - 1098-0121
VL  - 84
IS  - 13
PB  - American Physical Society
CY  - College Park
ER  - 
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  - Decker, Régis
A1  - Born, Artur
A1  - Büchner, Robby
A1  - Ruotsalainen, Kari
A1  - Stråhlman, Christian
A1  - Neppl, Stefan
A1  - Haverkamp, Robert
A1  - Pietzsch, Annette
A1  - Föhlisch, Alexander
T1  - Measuring the atomic spin-flip scattering rate by x-ray emission spectroscopy
JF  - Scientific reports
N2  - While extensive work has been dedicated to the measurement of the demagnetization time following an ultra-short laser pulse, experimental studies of its underlying microscopic mechanisms are still scarce. In transition metal ferromagnets, one of the main mechanism is the spin-flip of conduction electrons driven by electron-phonon scattering. Here, we present an original experimental method to monitor the electron-phonon mediated spin-flip scattering rate in nickel through the stringent atomic symmetry selection rules of x-ray emission spectroscopy. Increasing the phonon population leads to a waning of the 3d -> 2p(3/2) decay peak intensity, which reflects an increase of the angular momentum transfer scattering rate attributed to spin-flip. We find a spin relaxation time scale in the order of 50 fs in the 3d-band of nickel at room temperature, while consistantly, no such peak evolution is observed for the diamagnetic counterexample copper, using the same method.
Y1  - 2019
U6  - https://doi.org/10.1038/s41598-019-45242-8
SN  - 2045-2322
VL  - 9
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  - 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  - 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  - Eckert, Sebastian
A1  - Beye, Martin
A1  - Pietzsch, Annette
A1  - Quevedo, Wilson
A1  - Hantschmann, Markus
A1  - Ochmann, Miguel
A1  - Ross, Matthew
A1  - Minitti, Michael P.
A1  - Turner, Joshua J.
A1  - Moeller, Stefan P.
A1  - Schlotter, William F.
A1  - Dakovski, Georgi L.
A1  - Khalil, Munira
A1  - Huse, Nils
A1  - Föhlisch, Alexander
T1  - Principles of femtosecond X-ray/optical cross-correlation with X-ray induced transient optical reflectivity in solids
JF  - Applied physics letters
N2  - The discovery of ultrafast X-ray induced optical reflectivity changes enabled the development of X-ray/optical cross correlation techniques at X-ray free electron lasers worldwide. We have now linked through experiment and theory the fundamental excitation and relaxation steps with the transient optical properties in finite solid samples. Therefore, we gain a thorough interpretation and an optimized detection scheme of X-ray induced changes to the refractive index and the X-ray/optical cross correlation response. (C) 2015 AIP Publishing LLC.
Y1  - 2015
U6  - https://doi.org/10.1063/1.4907949
SN  - 0003-6951
SN  - 1077-3118
VL  - 106
IS  - 6
PB  - American Institute of Physics
CY  - Melville
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  - Yin, Zhong
A1  - Rajkovic, Ivan
A1  - Kubicek, Katharina
A1  - Quevedo, Wilson
A1  - Pietzsch, Annette
A1  - Wernet, Philippe
A1  - Föhlisch, Alexander
A1  - Techert, Simone
T1  - Probing the Hofmeister effect with ultrafast core-hole spectroscopy
JF  - The journal of physical chemistry : B, Condensed matter, materials, surfaces, interfaces & biophysical chemistry
N2  - In the current work, X-ray emission spectra of aqueous solutions of different inorganic salts within the Hofmeister series are presented. The results reflect the direct interaction of the ions with the water molecules and therefore, reveal general properties of the salt-water interactions. Within the experimental precision a significant effect of the ions on the water structure has been observed but no ordering according to the structure maker/structure breaker concept could be mirrored in the results indicating that the Hofmeister effect if existent may be caused by more complex interactions.
Y1  - 2014
U6  - https://doi.org/10.1021/jp504577a
SN  - 1520-6106
VL  - 118
IS  - 31
SP  - 9398
EP  - 9403
PB  - American Chemical Society
CY  - Washington
ER  -