Abstract
The emission spectra of the à 2Σ+ → [Xtilde] 2Π i transitions of HBS+ and DBS+ have been obtained by electron impact excitation. A vibronic analysis of the band systems has been made and the vibrational frequencies of the three modes in the [Xtilde] 2Π i state, and two in the à 2Σ+ state have been obtained for various isotopic derivatives. Renner and Fermi resonance effects of the bands involving the excitation of the ν2/″ mode have been considered and the parameters characterizing these interactions evaluated.