STRUCTURE OF THE ICE NANOCRYSTAL SURFACE FROM SIMULATED VERSUS EXPERIMENTAL SPECTRA OF ADSORBED CF4

CF4 adsorbate uptake and spectra are simulated on various model icy su rfaces and compared to experimental data measured for CR adsorbate on ice nanocrystals. Comparison suggests that surfaces of annealed ice na nocrystals are relatively smooth but laterally disordered, while surfa ces of unannealed nanocrystals are disordered and rough. CF4 adsorbate structure and uptake display remarkable sensitivity to the structural features of the ice surface models and in particular to the extent of disorder. Asymmetric CF stretch spectroscopy of CF4 adsorbate is sugg ested as a useful probe of the surface structure of molecular solids a nd of large molecular clusters.