Optical and Dielectric Properties of Water in the Vacuum Ultraviolet

Abstract

The optical and dielectric properties of water in the vacuum ultraviolet are presented and discussed. Optical constants at energies up to 14.6 eV were obtained by a Kramers-Kronig analysis using reflectances measured in this study between 9.2 and 14.9 eV and reflectances calculated from data in the literature below 9.9 eV. Structure in the complex part of the dielectric constant and the energy-loss function of water is compared with molecular excitations observed in water vapor. A sum-rule calculation indicates approximately 1 as the effective number of electrons per water molecule participating in absorption processes in the liquid state up to 14.6 eV.