Electronic Structures of Water and Ice

Abstract

Electronic structures of water and ice are investigated by means of XPS, UPS and VUV absorption spectroscopy. All the bands found in the XPS spectra of ice show a fairly good agreement with the electronic band structure theoretically calculated for cubic ice using molecular tight binding approximation. From the UPS spectra the vacuum level of ice is found at 10.5 eV above the top of the valence band, and a conduction band level of high density of states at 3.5 eV above the vacuum level. In VUV spectra D₂O ice film shows a well separated absorption band at 8.75 eV, whose shape is almost independent of temperature, and it is suggested that ice is essentially a kind of molecular crystal. The absorption coefficients in the tail regions of the fundamental absorption bands of water and ice show nearly exponential dependence on the photon energy, and they seem to be well expressed as the tail of a Gaussian band.