Laser photoelectron spectroscopy of the formyl anion

Abstract

The 488 nm photoelectron spectra of HCO− and DCO− show vibrational structure in the X̃ 2A′ state of neutral formyl radical up to 10 000 cm−1 above the vibrational ground state. Electron affinities are found to be 0.313±0.005 eV for HCO and 0.301±0.005 eV for DCO. The CH bond strength and heat of formation of HCO− and the gas phase acidity of formaldehyde are derived from these data. A Franck–Condon analysis of the photoelectron spectra provides an estimate of the equilibrium geometry of the anion. Transitions to excited vibrational states of HCO enable the determination of a complete set of quadratic anharmonicities.