Effects of phase density on ionization processes and electron localization in fluids

Abstract

In this paper we shall be concerned with the energetics of selective ionization processes in simple nonpolar fluids and with the nature of electron localization in polar fluids, studied over a wide density range. The static features of bound Wannier states and of the conduction band in simple solid and fluid insulators were monitored by vacuum-ultraviolet absorption spectroscopy and photoemission studies providing quantitative information concerning the energy of the bottom of the conduction band, impurity ionization potentials, and adiabatic polarization energies. Electron localization in subcritical and supercritical water and ammonia was studied by pulse radiolysis methods. A critical, temperature dependent, density ρC for electron localization in ND3 was observed. The weak density dependence of the maximum of the absorption band of the localized electron in D2O and ND3, and the temperature and density dependence of ρC in ND3, provide compelling evidence for the crucial role of density fluctuations on electron localization in polar fluids.