A5055126491- Advanced Chemical Physics Studies
- X-ray Spectroscopy and Fluorescence Analysis
- Spectroscopy and Quantum Chemical Studies
- Atomic and Molecular Physics
- Advanced NMR Techniques and Applications
- Crystallography and Radiation Phenomena
- Inorganic Fluorides and Related Compounds
- Machine Learning in Materials Science
- Nuclear Physics and Applications
- Catalysis and Oxidation Reactions
- Mass Spectrometry Techniques and Applications
- Chemical Thermodynamics and Molecular Structure
- Photochemistry and Electron Transfer Studies
- Radical Photochemical Reactions
- Molecular Spectroscopy and Structure
- Laser-Matter Interactions and Applications
- X-ray Diffraction in Crystallography
- Metal complexes synthesis and properties
- Atmospheric chemistry and aerosols
- Iron oxide chemistry and applications
- Perovskite Materials and Applications
- Ammonia Synthesis and Nitrogen Reduction
- Strong Light-Matter Interactions
- Spectroscopy and Laser Applications
- Magnetism in coordination complexes
KTH Royal Institute of Technology
2016-2025
Stockholm University
2022
Uppsala University
2018-2022
Universidade Federal de Goiás
2016-2017
The developments of the open-source OpenMolcas chemistry software environment since spring 2020 are described, with a focus on novel functionalities accessible in stable branch package or via interfaces other packages. These span wide range topics computational and presented thematic sections: electronic structure theory, spectroscopy simulations, analytic gradients molecular optimizations, ab initio dynamics, new features. This report offers an overview chemical phenomena processes can...
Local probes of the electronic ground state are essential for understanding hydrogen bonding in aqueous environments. When tuned to dissociative core-excited at O1s pre-edge water, resonant inelastic X-ray scattering back exhibits a long vibrational progression due ultrafast nuclear dynamics. We show how coherent evolution OH bonds around oxygen provides access high levels liquid water. The stretch into long-range part potential energy curve, which makes probe more sensitive than infra-red...
Electronically excited states play important roles in many chemical reactions and spectroscopic techniques. In quantum chemistry, a common technique to solve is the multiroot Davidson algorithm, but it not designed for processes like X-ray spectroscopy that involves hundreds of highly states. We show how use restricted active space wavefunction together with projection operator remove low-lying electronic offers an efficient way reach single double-core-hole Additionally, several...
Abstract The dynamics of fragmentation and vibration molecular systems with a large number coupled degrees freedom are key aspects for understanding chemical reactivity properties. Here we present resonant inelastic X-ray scattering (RIXS) study to show how it is possible break down such complex multidimensional problem into elementary components. Local multimode nuclear wave packets created by excitation different core-excited potential energy surfaces (PESs) will act as spatial gates...
The x-ray absorption spectrum of N_{2}^{+} in the K-edge region has been measured by irradiation ions stored a cryogenic radio frequency ion trap with synchrotron radiation. We interpret experimental results help restricted active space multiconfiguration theory. Spectroscopic constants 1σ_{u}^{-1} ^{2}Σ_{u}^{+} state, and two 1σ_{u}^{-1}3σ_{g}^{-1}1π_{g} ^{2}Π_{u} states are determined from measurements. charge ground state together spin coupling involving several open shells give rise to...
In this combined theoretical and experimental study we report a full analysis of the resonant inelastic X-ray scattering (RIXS) spectra H2O, D2O HDO. We demonstrate that electronically-elastic RIXS has an inherent capability to map potential energy surface perform vibrational electronic ground state in multimode systems. show control selection excitation can be performed by tuning frequency across core-excited molecular bands is clearly reflected spectra. Using high level ab initio structure...
In this combined theoretical and experimental study we report on an analysis of the resonant inelastic X-ray scattering (RIXS) spectra gas phase water via lowest dissociative core-excited state |1s-1O4a11. We focus spectral feature near dissociation limit electronic ground state. show that narrow atomic-like peak consists overlapping contribution from RIXS channels back to first valence excited |1b-114a11 molecule. The has signatures ultrafast (UFD) in state, as by means ab initio...
We report on a combined theoretical and experimental study of core-excitation spectra gas liquid phase methanol as obtained with the use X-ray absorption spectroscopy (XAS) resonant inelastic scattering (RIXS). The electronic transitions are studied computational methods that include strict extended second-order algebraic diagrammatic construction [ADC(2) ADC(2)-x], restricted active space perturbation theory, time-dependent density functional theory—providing complete assignment near oxygen...
We present and analyze high resolution near edge X-ray absorption fine structure (NEXAFS) spectra of CO+ at the carbon oxygen K-edges. The show a wealth features that appear very differently two analysis these can be divided into three parts; (i) repopulation transition to open shell orbital - here C(1s) or O(1s) 5σ transition, where normal core hole state is reached from different initial interaction than in photoelectron spectroscopy; (ii) spin coupled split valence bands corresponding π*...
Strong and ultrastrong coupling via nanostructures can be considered a tool for optimizing photochromic organic molecular systems solar cell applications.
In this article the recent developments of open-source OpenMolcas chemistry software environment, since spring 2020, are described, with main focus on novel functionalities that accessible in stable branch package and/or via interfaces other packages. These community span a wide range topics computational chemistry, and presented thematic sections associated electronic structure theory, spectroscopy simulations, analytic gradients molecular optimizations, ab initio dynamics, new features....
The capability of the multiconfigurational restricted active space approach to identify electronic structure from spectral fingerprints is explored by applying it iron L-edge X-ray absorption spectroscopy (XAS) three heme systems that represent limiting descriptions in Fe–O2 bond, ferrous and ferric [Fe(P)(ImH)2]0/1+ (P = porphine, ImH imidazole), FeII(P). level agreement between experimental simulated shapes calculated using cosine similarity, which gives a quantitative unbiased assignment....
As an example of symmetry breaking in NEXAFS spectra protonated species we present a high resolution spectrum dinitrogen, the diazynium ion N 2 H + .
The concept of the potential-energy surface (PES) and directional reaction coordinates is backbone our description chemical mechanisms. Although eigenenergies nuclear Hamiltonian uniquely link a PES to its spectrum, this information in general experimentally inaccessible large polyatomic systems. This due (near) degenerate rovibrational levels across parameter space all degrees freedom, which effectively forms pseudospectrum given by centers gravity groups close-lying vibrational levels. We...
We present a detailed experimental-theoretical analysis of O $K$-edge resonant $1\ensuremath{\sigma}\ensuremath{-}2\ensuremath{\pi}$ inelastic x-ray scattering (RIXS) from carbon monoxide with unprecedented energy resolution. employ high-level ab initio calculations to compute the potential curves states involved in RIXS process and simulate measured spectra using wave-packet-propagation formalism, including Coulomb coupling final-state manifold. The theoretical allows us explain all key...
Abstract As is well established, the symmetry breaking by isotope substitution in water molecule results localisation of vibrations along one two bonds ground state. In this study we find that may be broken excited electronic states. Contrary to state, stretching HDO are delocalised bound "Equation missing"<!-- image only, no MathML or LaTex --> core-excited state spite mass difference between hydrogen and deuterium. The reason for effect can traced narrow “canyon-like” shape potential...
We develop a theory of infrared (IR)-pump--x-ray-probe spectroscopy for molecular studies. illustrate advantages the proposed scheme by means numerical simulations employing vibrational wave packet technique applied to x-ray absorption and resonant inelastic scattering (RIXS) spectra water molecule vibrationally excited preceding IR field. The promotion dissociative $1{a}_{1}^{\ensuremath{-}1}4{a}_{1}$ bound $1{a}_{1}^{\ensuremath{-}1}2{b}_{2}$ core-excited states with qualitatively...
Abstract The unique opportunity to study and control electron-nuclear quantum dynamics in coupled potentials offered by the resonant inelastic X-ray scattering (RIXS) technique is utilized unravel an anomalously strong two-electron one-photon transition from core-excited Rydberg final states CO molecule. High-resolution RIXS measurements of energy region 12–14 eV are presented analyzed means simulations using wave packet propagation formalism ab initio calculations potential curves dipole...
X-ray processes involve interactions with high-energy photons. For these short wavelengths, the perturbing field cannot be treated as constant, and there is a need to go beyond electric-dipole approximation. The exact semi-classical light-matter interaction operator offers several advantages compared multipole expansion such improved stability ease of implementation. Here, used model x-ray scattering in metal K pre-edges. This relativistic two-photon process where absorption dominated by...
It is well established that different electronic channels, in resonant inelastic x-ray scattering (RIXS), display polarization dependences due to orientations of their corresponding transition dipole moments the molecular frame. However, this effect does not influence vibrational progression Franck-Condon approximation. We have found core excitation and deexcitation experience ultrafast rotation during dissociation intermediate core-excited state. This makes RIXS sensitive photons. study...
Experimental near-edge x-ray-absorption fine-structure (NEXAFS) spectra of the nitrosonium ${\mathrm{NO}}^{+}$ ion are presented and theoretically analyzed. While neutral NO has an open shell, cation is a closed-shell species, which for NEXAFS leads to simplicity spectrum. Compared NO, electrons in experience stronger Coulomb potential, introduces shift ionization potential towards higher energies, depletion intensity large interval above ${\ensuremath{\pi}}^{*}$ resonance,...
In this article the recent developments of open-source OpenMolcas chemistry software environment, since spring 2020, are described, with main focus on novel functionalities that accessible in stable branch package and/or via interfaces other packages. These community span a wide range topics computational chemistry, and presented thematic sections associated electronic structure theory, spectroscopy simulations, analytic gradients molecular optimizations, ab initio dynamics, new features....
Using a magnetic bottle multi-electron time-of-flight spectrometer in combination with synchrotron radiation, double-core-hole pre-edge and continuum states involving the K-shell of carbon atoms n-butane (n-C4H10) have been identified, where ejected core electron(s) emitted Auger electrons from decay such detected coincidence. An assignment main observed spectral features is based on results multi-configurational self-consistent field (MCSCF) calculations for excitation energies static...