Photoelectron spectroscopy and the geometry of the phosphine and phosphorous trifluoride molecular ions

Abstract

The lowest energy ionization process in phosphine and phosphorous trifluoride produces a vibrational progression. The detailed structure of the photoelectron spectrum suggests that the ground ionic state of phosphorous trifluoride is very probably strictly planar, while that of phosphine is pyramidal with a very small barrier to inversion. The bonding character of electrons in the 2e molecular orbital of phosphine is discussed in terms of the second band in the photoelectron spectrum, its vibrational fine structure and the Jahn-Teller splitting. A HeII photoelectron spectrum of phosphorous trifluoride reveals a further ionization potential and gives a significantly different intensity distribution.