Dissociation behavior of hydrogen bromide dications investigated using multielectron–ion coincidence spectroscopy

The dissociation behavior of hydrogen bromide dications (HBr2+) produced by the Auger decay of Br 3d core-hole states in HBr was investigated using multielectron–ion coincidence spectroscopy. Coincidence detection of 3d photoelectrons, the associated Auger electrons, and ions was conducted to identify the metastability and dissociation pathways of individual electronic states in the dications. Vibration levels v = 0–3 of the X3Σ− ground state and v = 0 of the a1Δ state survive beyond 10 μs, whereas the v ≥ 1 level of the a1Δ state exhibits predissociation on the submicrosecond timescale. Higher electronic states promptly dissociate into H+ + Br+ or H + Br2+ fragments.