Shape resonance effects in the photoabsorption spectra of BF3

Abstract

Multiple-scattering model calculations of cross sections for dipole transitions from all occupied orbitals of BF3 to excited bound states and continuum states of electron kinetic energy <30 eV are presented. The photoelectron angular distribution asymmetry parameters β are also given for all occupied orbitals. The boron and fluorine K-shell calculations are in qualitative agreement with, and provide a clear interpretation of, the measured spectra. Two shape resonances are found in the low energy continuum: one of a′1 symmetry, the other of e′ symmetry. The resonances are found to be due to trapping of p waves on the fluorine atoms. This atomic localization as well as the dominance of low-l partial waves outside the molecule put these shape resonances in a class distinct from those observed in diatomic molecules.