Unified description of temperature-dependent hydrogen-bond rearrangements in liquid water

TLDR

Liquid water’s unique properties arise from its highly directional hydrogen‑bond network, yet a coherent description of this network—whether continuum or multicomponent—has remained elusive despite decades of study, with the temperature dependence of its Raman spectrum often cited as evidence for a multistate system. Our combined experimental and theoretical study demonstrates that the Raman spectral features previously attributed to a multistate system arise from a continuous hydrogen‑bond distribution, supporting a locally tetrahedral description of liquid water. Reference: Wernet et al., Science 304, 995–999 (2004).

Abstract

The unique chemical and physical properties of liquid water are a direct result of its highly directional hydrogen-bond (HB) network structure and associated dynamics. However, despite intense experimental and theoretical scrutiny spanning more than four decades, a coherent description of this HB network remains elusive. The essential question of whether continuum or multicomponent (“intact,” “broken bond,” etc.) models best describe the HB interactions in liquid water has engendered particularly intense discussion. Most notably, the temperature dependence of water's Raman spectrum has long been considered to be among the strongest evidence for a multicomponent distribution. Using a combined experimental and theoretical approach, we show here that many of the features of the Raman spectrum that are considered to be hallmarks of a multistate system, including the asymmetric band profile, the isosbestic (temperature invariant) point, and van't Hoff behavior, actually result from a continuous distribution. Furthermore, the excellent agreement between our newly remeasured Raman spectra and our model system further supports the locally tetrahedral description of liquid water, which has recently been called into question [Wernet, P., et al. (2004) Science 304, 995-999].