The influence of non-adiabatic effects on the outer valence shell photoionisation dynamics of boron trifluoride Original Research Article

The entire valence shell photoelectron spectrum of boron trifluoride has been studied using synchrotron radiation in the photon energy range 20–120 eV. Photoelectron angular distributions and branching ratios for the six outer valence orbitals have been measured and compared with theoretical predictions. The strongest evidence for the e′ shape resonance affecting the valence shell photoionisation dynamics appears in the asymmetry parameter associated with the 4a1′ orbital. Strong vibronic coupling effects are observed in the vibrational structure exhibited by the E 2A1′ state and asymmetry parameters are reported for several vibrational components. The data demonstrate that the asymmetry parameters associated with the photoelectron peaks induced through vibronic coupling are characteristic of the ionic state through which they derive their intensity. Complex structure, associated with ionisation from the 2e′ and 3a1′ inner valence orbitals, is observed in the photoelectron spectrum for binding energies between 26 and 50 eV. This structure is compared with pole strengths calculated using the many-body Greenʹs function approach.