Interfacial reaction of water ice on polycrystalline vanadium and its effects on thermal desorption of water

Abstract

Thermal desorption and decomposition of water ice deposited onto a polycrystalline V surface were investigated using temperature-programmed desorption and secondary ion mass spectrometry. The water molecules in multilayer films dissociate preferentially at the interface, whereas water desorption from the surface is depressed considerably. The oxygen atoms (hydrogen molecules) formed at the interface are incorporated into the substrate (released into the gas phase) sequentially at temperatures higher than 140 K. The crystallization kinetics of water multilayers is not influenced by the interfacial reaction, but the water desorption rate is depressed by the interfacial reaction even after crystallization. Consequently, thermal desorption of water from the surface and its reaction at the interface are found to be correlated across thin films. This behavior is explainable as dynamic heterogeneity of water in the deeply supercooled region and premelting of metastable ice Ic, where mobile water molecules play a dominant role in both thermal desorption and the interfacial reaction.