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Hydrogen bonding and coordination in normal and supercritical water from X-ray inelastic scattering

Patrick H. -L. Sit·Christophe Bellin·Bernardo Barbiellini·D. Testemale·J. -L. Hazemann·T. Buslaps·Nicola Marzari·Abhay Shukla
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Abstract

A direct measure of hydrogen bonding in water under conditions ranging from the normal state to the supercritical regime is derived from the Compton scattering of inelastically-scattered X-rays. First, we show that a measure of the number of electrons $n_e$ involved in hydrogen bonding at varying thermodynamic conditions can be directly obtained from Compton profile differences. Then, we use first-principles simulations to provide a connection between $n_e$ and the number of hydrogen bonds $n_{HB}$. Our study shows that over the broad range studied the relationship between $n_e$ and $n_{HB}$ is linear, allowing for a direct experimental measure of bonding and coordination in water. In particular, the transition to supercritical state is characterized by a sharp increase in the number of water monomers, but also displays a significant number of residual dimers and trimers.

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Patrick H. -L. Sit, Christophe Bellin, Bernardo Barbiellini, D. Testemale, J. -L. Hazemann, T. Buslaps, Nicola Marzari, Abhay Shukla. 2007-02-26. Hydrogen bonding and coordination in normal and supercritical water from X-ray inelastic scattering. https://doi.org/10.1103/physrevb.76.245413

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