Threshold resonances in the electron photodetachment spectrum of acetaldehyde enolate anion. Evidence for a low-lying, dipole-supported state

Abstract

The electron photodetachment spectra for the enolate anions of acetaldehyde and acetaldehyde‐d₃ have been measured using an ion cyclotron resonance spectrometer in conjunction with a tunable dye laser. Sharp resonances at threshold are observed for both anions, and are attributed to a low‐lying excited electronic state of the anion, which we relate to postulated ’’dipole‐supported’’ states of electron–polar molecule systems. The electron affinity of the neutral enolate radicals CH₂CHO and CD₂CDO are found to be 1.824±0.005 and 1.819±0.005 eV, respectively.