Crystal Growth in the Presence of Surface Melting: Novel Behavior of the Principal Facets of Ice

TL;DR

This study measures ice crystal growth rates from water vapor across temperatures -2°C to -40°C, revealing complex surface behaviors linked to surface melting and providing data for modeling ice surface structures.

Contribution

It provides detailed measurements of ice facet growth rates and parameters, highlighting the effects of surface melting on ice surface properties and offering data for molecular dynamics modeling.

Findings

Growth rates fit a layer-nucleation model

Surface melting affects growth parameters

Step energy varies with temperature

Abstract

We present measurements of the growth rates of the principal facet surfaces of ice from water vapor as a function of supersaturation over the temperature range -2 C > T > -40 C. Our data are well described by a dislocation-free layer-nucleation model, parameterized by the attachment coefficient as a function of supersaturation \alpha(\sigma) = Aexp(-\sigma_0/\sigma). The measured parameters A(T) and \sigma_0(T) for the basal and prism facets exhibit a complex behavior that likely originates from structural changes in the ice surface with temperature, in particular the onset and development of surface melting for T > -15 C. From \sigma_0(T) we extract the terrace step energy \beta(T) as a function of temperature for both facet surfaces. As a basic property of the equilibrium ice surface, the step energy \beta(T) may be amenable to calculation using molecular dynamics simulations, potentially yielding new insights into the enigmatic surface structure of ice near the triple point.