Calculated vibrational structure of the first band of the photoelectron spectrum of HO2- and the electron affinity of HO2

The vibrational structure of the first band of the photoelectron (PE) spectrum of HO2- and DO2- has been calculated on the basis of (slightly modified) ab initio potentials. The best agreement with the experimental spectrum of HO2- is obtained for a vibrational temperature of ca. 600 K. ''Peak D'', which has been under debate in earlier work, is composed of two transitions, with the ''hot'' transition 3(1)(1) being more intense than the adiabatic transition. Since the nu(2) bending mode of DO2 has significant OO stretching character, the vibrational structure of the PE spectrum of DO2- is more complex than that of HO2-. Large-scale RCCSD(T) calculations of the equilibrium electron affinity of HO2 yield 1.058 eV which agrees with the experimental value of 1.044 +/- 0.020 eV.