PNNL

Abstract

e have investigated the nucleation and growth of crystalline ice in 0.24 µm thick, supercooled water films deposited on Pt(111) at cryogenic temperatures. The films were heated with ~10 ns infrared laser pulses, which produced typical heating and cooling rates of ~109 – 1010 K/s. The crystallization of these water films was monitored with infrared spectroscopy. The experimental conditions were chosen such that ice nucleation at the water/metal interface was suppressed and nucleation at the water/vacuum interfaces did not affect the observations. Since the water films were flat, their internal pressure was not raised due to curvature effects. Therefore, the experiments were sensitive to the homogeneous ice nucleation rate in the temperature range from ~210 K to 225 K. The experiments show that the maximum for the homogeneous ice nucleation rate versus temperature, Jmax, needs to be = 1026 m-3s-1 and is likely to be ~1029±2 m-3s-1. We argue that such large nucleation rates are consistent with experiments on hyperquenched glassy water, which typically have crystalline fractions of ~1% or more.