The Electronic Structures of Condensed Materials Studied by Ultraviolet Photoelectron Spectroscopy

Abstract

The so lid phase ultraviolet photoelectron spectra of water, carbon disulfide, benzene, N-methylaniline, and pentane condensed on a gold substrate at 77 K were measured. The features of the spectra are similar to those of the corresponding gas phase spectra. The difference between the gas and solid phase IP’s, the relaxation shift, is nearly constant for each compound studied except for the case of water, where the 3a₁ molecular orbital state in solid is affected by the hydrogen bonding. The values of the relaxation shift for water, benzene and carbon disulfide are 1.1–1.3eV, while those for N-methylaniline and pentane are 0.6 and 0.7 eV, respectively. The small values for the latter compounds are due to the fact that the molecules are loosely packed in the solids. The mechanisms of the band broadening for the molecular crystal are discussed in relation to the spectrum of solid carbon disulfide. For N-methylaniline the spectra of the gas, liquid and solid phases were compared. To our knowledge, this is the first case in which the electronic structures of all the three phases are studied by ultraviolet photoelectron spectroscopy.