Structure and energetics of vinoxide and the X(²A″) and A(²A′) vinoxy radicals

The photoelectron spectrum of vinoxide, C₂H₃O^-, at 355 nm is reported, showing photodetachment to both the X(²A″) ground and first excited A(²A′) states of the vinoxy radical. Both direct interpretations and FranckCondon simulations of the photoelectron spectrum of this simple enolate anion have been used to obtain insights into the energetics and structures of the anion and the ground and first excited state of the neutral radical. Franck-Condon simulations were generated from ab initio geometry and frequency calculations using the CASSCF method and showed good agreement with the vibrational structure visible in the experimental spectrum. The electron affinity (E.A._exp = 1.795 ±0.015 eV; E.A._calc = 1.82 eV) and separation energy of the ground and first excited states (T_0,exp = 1.015 ±0.015 eV; T_0,calc = 0.92 eV) obtained from the ab initio calculations are in good accord with the experimental values.