Photodetachment Imaging Study of the Vinoxide Anion

A photodetachment imaging study of the photoelectron angular distributions produced by the 354.8-nm photodetachment of the vinoxide anion, H 2 C CHO -, is reported. The photoelectron angular distributions for both the X̃ 2 A ‘ ‘ ground state and à 2 A ‘ excited state of the neutral vinoxy radicals were measured. Energy-dependent photoelectron anisotropy parameters are reported for both electronic states. Photodetachment from the HOMO of the anion (the CCO nonbonding π(a‘ ‘) orbital) yields ground-state vinoxy radicals and exhibits a sin 2 θ angular dependence (β ( X̃ 2 A ‘ ‘ ) = −0.7 ± 0.1) relative to the electric vector of the laser. Photodetachment from the HOMO-1 of the anion (the oxygen σ 2px (a‘) orbital) yields excited-state à 2 A ‘ radicals and exhibits a cos 2 θ angular dependence (β ( à 2 A ‘ ) = 0.6 ± 0.1) of the photoelectrons. These results are qualitatively interpreted in terms of the electronic structure of the anion−neutral system.