Structure and Phonons of the Ice Surface

Abstract

The structure and phonon dynamics of the ice surface, prepared by growing thick ice layers ( $\ensuremath{\sim}100\AA{}$) on Pt(111), were investigated using high resolution helium atom scattering. Ice layers grown at ${T}_{s}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}125\mathrm{K}$ were found to be well ordered, with a complete bilayer ( $1\ifmmode\times\else\texttimes\fi{}1$) surface termination, as shown by diffraction measurements at ${T}_{s}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}30\mathrm{K}$. Time-of-flight spectra provide evidence for an intense longitudinal shearing mode, large multiphonon background, and enhanced vibrational amplitudes at the surface, which are consistent with dynamic disorder and a large accommodation coefficient at the surface.