Relationship between x-ray emission and absorption spectroscopy and the local H-bond environment in water

Zhovtobriukh, Iurii and Besley, Nicholas A. and Fransson, Thomas and Nilsson, Anders and Pettersson, Lars G.M. (2018) Relationship between x-ray emission and absorption spectroscopy and the local H-bond environment in water. Journal of Chemical Physics, 148 (14). 144507/1-144507/. ISSN 1089-7690

[img]
Preview
PDF - Requires a PDF viewer such as GSview, Xpdf or Adobe Acrobat Reader
Download (2MB) | Preview

Abstract

The connection between specific spectrum features in the water X-ray absorption (XAS) and X-ray emission (XES) spectra and the local H-bond coordination is studied based on structures obtained from path-integral molecular dynamics simulations using either the opt-PBE-vdW density functional or the MB-pol force field. Computing the XES spectrum using all molecules in a snapshot results in only one peak in the lone-pair (1b1) region while the experiment shows two peaks separated by 0.8-0.9 eV. Different H-bond configurations were classified based on the local structure index (LSI) and a geometrical H-bond cone criterion. We find that tetrahedrally coordinated molecules characterised by high LSI values and two strong donated and two strong accepted H-bonds contribute to the low energy 1b1 emission peak and to the post-edge region in absorption. Molecules with asymmetric H-bond environment with one strong accepted and one strong donated H-bond and low LSI values give rise to the high energy 1b1 peak in the emission spectrum and mainly contribute to the pre-edge and main-edge in the absorption spectrum. The 1b1 peak splitting can be increased to 0.62 eV by imposing constraints on the H-bond length, i.e. for very tetrahedral structures short H-bonds (less than 2.68 Å) and for very asymmetric structures elongated H-bonds (longer than 2.8 Å). Such structures are present, but underrepresented, in the simulations which give more of an average of the two extremes.

Item Type: Article
Additional Information: This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. The following article appeared in Iurii Zhovtobriukh, Nicholas A. Besley,Thomas Fransson, Anders Nilsson, and Lars G. M. Pettersson Relationship between x-ray emission and absorption spectroscopy and the local H-bond environment in water The Journal of Chemical Physics 2018 148:14 and may be found at https://aip.scitation.org/doi/full/10.1063/1.5009457
Schools/Departments: University of Nottingham, UK > Faculty of Science > School of Chemistry
Identification Number: https://doi.org/10.1063/1.5009457
Depositing User: Besley, Nick
Date Deposited: 21 Mar 2018 13:25
Last Modified: 16 Apr 2018 08:44
URI: http://eprints.nottingham.ac.uk/id/eprint/50560

Actions (Archive Staff Only)

Edit View Edit View