Oxygen disorder in ice probed by X-ray Compton scattering

TL;DR

This study employs X-ray Compton scattering to analyze oxygen disorder in various ice phases, revealing phase-specific electron momentum signatures and quantifying oxygen site disorder during phase transitions.

Contribution

It introduces a novel approach combining electron momentum density and position space analysis to quantify oxygen disorder in ice phases.

Findings

Quantitative agreement between theory and experiment for ice VIII.

Identification of signatures of oxygen disorder in momentum density.

Determination of the fraction of electrons involved in phase transitions.

Abstract

We use electron momentum density in ice as a tool to quantify order-disorder transitions by comparing Compton profiles differences of ice VI, VII, VIII and XII with respect to ice Ih. Quantitative agreement is found between theory and experiment for ice VIII, which is the most ordered phase. Robust signatures of the oxygen disorder are identified in the momentum density for the VIII-VII ice phase transition. The unique aspect of this work is the determination of the fraction n_e of electron directly involved in phase transitions as well as the use of position space signatures for quantifying oxygen site disorder.