ELECTRONIC-STRUCTURE OF THE VALENCE BANDS OF SOLID NH3 AND H2O STUDIED BY ULTRAVIOLET PHOTOELECTRON-SPECTROSCOPY

The results of a photoelectron study using ultraviolet 40.81 eV photons (UPS) of the outermost bands of the molecular solids NH3 and H2O are reported. The binding energies, the energy separation, the band widths and the branching ratio of the two outermost bands of solid NH3 are found not to be significantly different from the 3al and 1e molecular orbital states of the gaseous NH3 UPS spectrum. This implies that hydrogen bonding has not produced any significant change in the electronic structure of the valence bands of solid NH3. Because of a much smaller intermolecular hydrogen bond length in solid H2O compared to that in solid NH3, the hydrogen bond does, however, produce a significant change in the valence bands of H2O on solidification, and because of the orbital geometry it predominantly affects the 3al molecular orbital state. © 1979.