On the electronic structure of liquid water: Conduction-band tail revealed by photoionization data

Abstract

The photoionization yield curves ▪ as a function of photon energy E ph of pure water or dilute aqueous solutions display an exponential behavior in the ionization threshold region. This suggests that these curves reflect the existence of an Urbach tail lying below the conduction-band edge of water. A quantitative treatment of various reported photoionization data provides an experimental basis for the determination of the energy distribution of electron trap states in the conduction-band tail of water and presents a picture of the electronic structure of liquid water which is coherent with previous results of photoelectron emission spectroscopy.