Feshbach resonances in electron excitation functions of HBr

Electron impact excitation functions for b 3 Pi 1 , b 3 Pi 0 and C 1 Pi states of HBr have been measured in an energy range from threshold to 2.5 eV above and for scattering angles from 40 degrees to 120 degrees . Strong threshold excitation and a large number of structures in the investigated energy range are interpreted in terms of resonances, reported by Spence and Noguchi (1975) in a transmission experiment. A new resonance has been found at 10.15 eV appearing strongly at large angles in the states involving the ( 2 Pi 1 2/) core. The almost constant value of the energy separation between the members of the resonance pairs, selectivity of resonance decay with respect to the excited state ionic core and observed angular dependences have been used in discussing the resonance state assignments.