Ab Initio Study of the Electronic Spectrum of HOBr

The structure and vibrational spectra of HOBr calculated using ab initio post-Hartree−Fock methods are in reasonable agreement with experiment. Vertical excitation energies and oscillator strengths have been computed for transitions to low-lying excited states of HOBr. The peaks at 350 and 280 nm in the gas-phase absorption spectrum reported by Orlando and Burkholder ( J . Phys . Chem . 1995, 99, 1143−1150) may be attributed to the à 1 A‘‘ and B̃ 1 A‘ states, respectively. The calculations predict another absorption with a maximum at about 477 nm due to the ã 3 A‘‘ state.