Structure and Energetics of Vinoxide and the X(²A‘ ‘) and A(²A‘) Vinoxy Radicals

Abstract

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 Franck−Condon 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.

Comparing electronic structure predictions for the ground state dissociation of vinoxy radicals

“…1-3 A number of experimental studies have examined the vibrational, 1,4,5 rotational, [5][6][7][8] and electronic structure 8,9 of vinoxy's ground ͑X 2 AЉ͒, first excited ͑A 2 AЈ͒, and second excited ͑B 2 AЉ͒ states. 1-3 A number of experimental studies have examined the vibrational, 1,4,5 rotational, [5][6][7][8] and electronic structure 8,9 of vinoxy's ground ͑X 2 AЉ͒, first excited ͑A 2 AЈ͒, and second excited ͑B 2 AЉ͒ states.…”

Photodissociation spectroscopy and dynamics of the CH2CFO radical

“…The vinoxy radical has two observed excited electronic states, which have been examined by absorption, 21 hole-burning spectroscopy, 22 LIF, [23][24][25][26][27] photodissociation, 28 and anion photoelectron spectroscopy. 29 Spectroscopic investigations of the B 2 AЉ state reveal that at energies approximately 1400 cm Ϫ1 above the origin, fluorescence is quenched by predissociation. [21][22][23][24][25][26]28 In fact, all vibrational levels of the CH 2 CHO B 2 AЉ state predissociate to CH 3 ϩCO and CH 2 COϩH photoproducts with a branching ratio estimated to be 1:4.…”

A novel conical intersection topography and its consequences: The 1, 2A2 conical intersection seam of the vinoxy radical

“…4 Its X 2 AЉ, à 2 AЈ, 5,6 and B 2 AЉ ͑Refs. [6][7][8][9][10] The à 2 AЈ state has been studied using photoelectron spectroscopy where a well-resolved spectrum for the low-lying vibrational levels has been observed. Theoretical descriptions of these states have also been reported.…”

“…5,7͒ electronic states have been studied experimentally. 6 In an experimental study, 7 photoexcitation to the B 2 AЉ state of vinoxy was observed to produce both H + H 2 CCO and CH 3 Direct production of the à 2 AЈ state by photodissociation of methylvinyl ether also yields both H + ketene ͓channel ͑1a͔͒ and CH 3 +CO ͓channel ͑1b͔͒. [6][7][8][9][10] The à 2 AЈ state has been studied using photoelectron spectroscopy where a well-resolved spectrum for the low-lying vibrational levels has been observed.…”