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

• Main Authors: Sit, Patrick H. -L, Bellin, Christophe, Barbiellini, Bernardo, Testemale, D, Hazemann, J. -L, Buslaps, T, Marzari, Nicola, Shukla, Abhay
• Format: Journal Article
• Language: English
• Published: 26.02.2007
• Subjects: Physics - Materials Science; Physics - Soft Condensed Matter
• DOI: 10.48550/arxiv.cond-mat/0702617

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.