Surface layering of liquids: The role of surface tension

TL;DR

This study investigates whether surface layering occurs in liquids, finding that metallic liquids exhibit layering regardless of surface tension, while water does not, indicating fundamental differences between dielectric and metallic liquids.

Contribution

The paper provides experimental evidence that water does not show surface layering at room temperature, contrasting with metallic liquids, and discusses implications for theories of surface structure.

Findings

Metallic liquids show surface layering regardless of surface tension.

Water does not exhibit surface layering at 298 K.

Fundamental differences exist between dielectric and metallic liquids' surface structures.

Abstract

Recent measurements show that the free surfaces of liquid metals and alloys are always layered, regardless of composition and surface tension; a result supported by three decades of simulations and theory. Recent theoretical work claims, however, that at low enough temperatures the free surfaces of all liquids should become layered, unless preempted by bulk freezing. Using x-ray reflectivity and diffuse scattering measurements we show that there is no observable surface-induced layering in water at T=298 K, thus highlighting a fundamental difference between dielectric and metallic liquids. The implications of this result for the question in the title are discussed.