Dissociative adsorption of hydrogen fluoride onto amorphous solid water

摘要

Adsorption of hydrogen fluoride (HF) onto amorphous solid water films at 50 K is reported to yielda strong absorbance continuum in their reflection-absorption infrared spectra (RAIRS). This andother complex features observed in the RAIRS spectra of stratified binary composite HF: H20nanoscopic films deposited onto Pt(111) are interpreted quantitatively using a classical optics model.Comparison with experimental data allows us to determine that the absorbance continuum is due toabsorption within the film (as opposed to trivial optical effects) and that the extent of intermixingand uptake is mostly limited to the first few molecular layers. Furthermore, extensive isotopescrambling is demonstrated by the observation of similar Zundel continua upon codeposition of neatHF, or DF, and H_2Ovapors onto Pt(111) at 50 K. These observations are consistent with thoseexpected from extensive ionic dissociation of HF upon dissolution within, and adsorption onto,ASW at 50 K.