Study of the OH and OD radicals with photoelectron spectroscopy using synchrotron radiation

Photoionization of the OH and OD radicals, produced from the H+NO2 and D+NO 2 reactions, has been studied in the gas phase in the photon energy region 13.0-17.0 eV using constant ionic state (CIS) and photoelectron spectroscop y (PES) employing synchrotron radiation. Structure in the CIS spectra, reco rded for the first and second photoelectron bands, has been assigned to exc itation to (a (1)Delta,3d) and (A (3)Pi,3d) Rydberg states. A comparison of vibrationally specific OH and OD CIS spectra, and photoelectron spectra re corded at resonant wavelengths, has allowed a more complete assignment of s tructure observed in earlier photoionization mass spectrometric measurement s These assignments have been supported by the results of Franck-Condon cal culations. The CIS spectra have been shown to be dominated by structure ari sing from excitation from the outermost valence molecular orbitals of OH [t he nonbonding 1 pi(O 2p) orbital and the bonding 3 sigma orbital] to O nd R ydberg orbitals. Photoelectron spectra recorded for the first bands of OH a nd OD at resonant photon energies have allowed more extensive vibrational s tructure to be obtained than has previously been recorded by PES experiment s performed with inert gas discharge photon sources. (C) 1999 American Inst itute of Physics. [S0021-9606(99)02201-1].