A1 Refereed original research article in a scientific journal
Full-dimensional theoretical description of vibrationally resolved valence-shell photoionization of H2O
Authors: Selma Engin, Jesús González-Vázquez, Gianluigi Grimaldi Maliyar, Aleksandar R. Milosavljević, Taishi Ono, Saikat Nandi, Denys Iablonskyi, Kuno Kooser, John D. Bozek, Piero Decleva, Edwin Kukk, Kiyoshi Ueda, Fernando Martín
Publisher: AMER INST PHYSICS
Publication year: 2019
Journal: Structural Dynamics
Journal name in source: STRUCTURAL DYNAMICS-US
Journal acronym: STRUCT DYN-US
Article number: ARTN 054101
Volume: 6
Issue: 5
Number of pages: 10
eISSN: 2329-7778
DOI: https://doi.org/10.1063/1.5106431
Web address : https://aca.scitation.org/doi/10.1063/1.5106431
Self-archived copy’s web address: https://research.utu.fi/converis/portal/detail/Publication/45336884
We have performed a full-dimensional theoretical study of vibrationally resolved photoelectron emission from the valence shell of the water molecule by using an extension of the static-exchange density functional theory that accounts for ionization as well as for vibrational motion in the symmetric stretching, antisymmetric stretching, and bending modes. At variance with previous studies performed in centrosymmetric molecules, where vibrationally resolved spectra are mostly dominated by the symmetric stretching mode, in the present case, all three modes contribute to the calculated spectra, including intermode couplings. We have found that diffraction of the ejected electron by the various atomic centers is barely visible in the ratios between vibrationally resolved photoelectron spectra corresponding to different vibrational states of the remaining H2O+ cation (the so-called v-ratios), in contrast to the prominent oscillations observed in K-shell ionization of centrosymmetric molecules, including those that only contain hydrogen atoms around the central atoms, e.g., CH4. To validate the conclusions of our work, we have carried out synchrotron radiation experiments at the SOLEIL synchrotron and determined photoelectron spectra and v-ratios for H2O in a wide range of photon energies, from threshold up to 150 eV. The agreement with the theoretical predictions is good.
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