MRD CI study of the electron affinity of HO 2 and the photodetachment energy of HO 2−

Abstract

Extended ab initio MRD CI electronic structure calculations are carried out on the ground state of HO 2 − and on the ground and first excited states of HO 2. Cuts of the potential energy surfaces along the OOH, bending and OOH coordinates are calculated in the neighbourhood of the equilibrium position and employed to compute the equilibrium geometry and fundamental vibrational frequencies of HO 2 −. Systematic calculations on the OO −, OHOH −, O 2O 2 − and HO 2 HO 2 − neutral-anion pairs indicate that the theoretical calculations underestimate the electron affinities by a nearly constant amount. Accordingly the EA (HO 2) is estimated to be 1.069±0.05 eV which is in good agreement with the measured value of 1.078 eV obtained from the HO 2 − photoelectron spectrum. The vertical and adiabatic electron affinities of HO 2 (X 2A″, A 2A′) and electron photodetachment energies of HO 2 − (X 1A′) to the X and A states of the neutral molecule are reported.