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Abstract

The spin polarization parameters A and xi , the cross section sigma and the angular distribution parameter beta in outer shell photoemission from HBr were measured in the resonance region of electronic autoionization between the HBr⁺ X ² Pi and HBr⁺ A ² Sigma ⁺ thresholds using photoelectron spectroscopy with circularly polarized synchrotron radiation. In this region the photoelectron spectra display pronounced vibrational excitation of the X ² Pi 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 sigma and A are combined to obtain cross sections for the outgoing partial waves. A comparison of the experimental results with ab initio MQDT calculations of Lefebvre-Brion(1989) indicates that predissociation is more important than theoretically predicted.