Comment on "Oxygen as a Site Specific Probe of the Structure of Water and Oxide Materials", PRL 107, 144501 (2011)

TL;DR

This paper comments on a neutron scattering study that used oxygen isotope substitution to analyze water's structure, highlighting progress and discrepancies with previous findings.

Contribution

It provides a critical analysis of a recent neutron scattering experiment on water, emphasizing the implications of oxygen isotope substitution for structural insights.

Findings

O-H bond length in light water is ~0.005A longer than in heavy water

Hydrogen bond peaks are at similar positions in both water types

The paper critiques the interpretation of experimental results

Abstract

A recent paper by Zeidler et al. (PRL 107, 144501 (2011)) describes a neutron scattering experiment on water in which oxygen isotope substitution is successfully achieved for the first time. Differences between scattering patterns with different oxygen isotopes give a combination of the O-O and O-H (or O-D) structure factors, and the method elegantly minimizes some of the problematic inelasticity effects associated with neutron scattering from hydrogen. Particular conclusions of the new work are that the OH bond length in the light water molecule is about 0.005A longer than the same bond in heavy water, and that the hydrogen bond peaks in both liquids are at about the same position. Notwithstanding the substantial progress demonstrated by the new work, the comparison with our own results (PRL, 101, 065502 (2008)) by Zeidler et al. is in our opinion misleading.