Dynamical and interference effects in X-ray emission spectroscopy of H-bonded water – origin of the split lone-pair peaks

Abstract

We examine the effects of core-hole-induced dynamics and vibrational interference on computed x-ray emission spectra of H-bonded water. Two model pentamers were investigated, tetrahedral and distorted, representing possible local environments in proposed low- and high-density water. Core-hole-induced dynamics were considered in the simulations, and the semi-classical Kramers-Heisenberg (SCKH) scheme to convolute theoretical spectra was applied. We determine the origin of the split two peaks in XES of liquid water to be a combination of the initial H-bonding and subsequent dynamics, where we find faster dynamics for tetrahedrally bonded. We further find that H-bond acceptors move towards the core-excited molecule while donors move away and we analyse the origin of this dynamics in terms of charge-redistributions during the dynamics. We determine the origin of the split two peaks in X-ray emission spectra of liquid water to be a combination of the initial H-bonding and subsequent dynamics, where we find faster dynamics for tetrahedrally H-bonded water. We further find that H-bond acceptors move towards the core-excited molecule while donors move away and we analyse the origin of this dynamics in terms of charge-redistributions during the dynamics.