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WaterPAD_Combined.pdf (5.67 MB)
Probing the Electronic Structure of Bulk Water at the Molecular Lengthscale with Angle-Resolved Photoelectron Spectroscopy
Preprints are manuscripts made publicly available before they have been submitted for formal peer review and publication. They might contain new research findings or data. Preprints can be a draft or final version of an author's research but must not have been accepted for publication at the time of submission.
revised on 19.05.2020 and posted on 20.05.2020by Samer Gozem, Robert Seidel, Uwe Hergenhahn, Evgeny Lugovoy, Bernd Abel, Bernd Winter, Anna I. Krylov, Stephen
We report a combined experimental and theoretical study of bulk water photoionization. Angular distributions of photoelectrons produced by ionizing the valence band of neat water using X-ray radiation (250-750 eV) show a limited (<30 %) decrease in the beta anisotropy parameter compared to the gas phase, indicating that the electronic structure of the individual water molecules can be probed. By theoretical modeling using high-level electronic structure methods, we show that in a high-energy regime photoionization of bulk can be described as an incoherent superposition of individual molecules, in contrast to a low-energy regime where photoionization probes delocalized entangled states of molecular aggregates. The two regimes-low energy versus high energy-are defined as limiting cases where the de Broglie wavelength of the photoelectron is either larger or smaller than the intermolecular distance between water molecules, respectively. The comparison of the measured and computed anisotropies reveals that at high kinetic energies the observed reduction in beta is mostly due to scattering rather than rehybridization due to solvation.