Rotationally resolved photoelectron spectra in resonance enhanced multiphoton ionization of SiF

Results of calculations of rotationally resolved photoelectron spectra for resonance enhanced multiphoton ionization (REMPI) of SiF via the B ²Σ⁺ (4sσ), C″ ²Σ⁺ (4pσ), and C′ ²Π (4pπ) Rydberg states are reported. In addition to the expected ΔN=even peaks, unusually strong ΔN=±1 transitions are predicted for photoionization of the B ²Σ⁺ state. These unusual transitions are due to even angular momentum components of the photoelectron matrix element and arise from the formation of Cooper minima in the ionization channels and strong l mixing in the electronic continuum induced by the nonspherical molecular ion potential. Unexpected ΔN=0,±2 transitions, due to odd wave contributions to the photoelectron matrix element, are also predicted for photoionization of the C″ ²Σ⁺ state. Asymmetrical ion distributions with respect to ΔN=0 are also predicted for the C′ ²Π state. Cooper minima are predicted to occur in the l=2 wave of the kπ photoelectron channel for the B state and in the l=4 wave of the kσ and kπ channels for the C″ state. Photoelectron angular distributions provide further insight into the photoionization dynamics.