Spin - resolved photoelectron spectroscopy of HBr in the resonance region of electron autoionization

The spin polarization parameters A and 5, the cross section c and the angular distribution parameter p in outer shell photoemission from HBr were measured in the resonance region of electronic autoionization between the HBr' X 'n and HBr+ A 5' thresholds using photoelectron spectroscopy with circularly polarized synchrotron radiation. In this region the photoelectron spectra display pronounced vibrational excitation of the x 'n final ionic states. The energy dependence of the dynamical parameters is strongly influenced by electronic autoionization and predissociation of vibrational progressions of Rydberg states. The data for CT and A are combined to obtain cross sections for the outgoing partial waves. A comparison of the experimental results with ob initio MQDT calculations of Lefebvre-Brion indicates that predissociation is more important than theoretically predicted.