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

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 ≥ T ≥ −40 C. Our data are well described by a dislocation-free layer-nucleationmodel, parameterized by the attachment coefficient as a function of supersaturation α(σ) = Aexp(−σ_0/σ). The measured parameters A(T) and σ_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 σ_0(T) we extract the terrace step energy β(T) as a function of temperature for both facet surfaces. As a basic property of the equilibrium ice surface, the step energy β(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.