STATE-SELECTIVE PREDISSOCIATION SPECTROSCOPY OF HYDROGEN BROMIDE IONS(HBR-(2)PI(I)(I=1() VIA THE (2)SIGMA(+)[)2, 3/2) TRANSITION/

The photodissociation of hydrogen bromide ions (HBr+) has been investi gated via the (2) Sigma(+)(v'=1, 2, 3, and 4) <-- (2) Pi(i)(i=1/2, 3/2 , v ''=0) transitions. The spectra reveal that state selective photodi ssociation with complete resolution of the rotational, orbital, and sp in angular momentum as well as the parity of the HBr+ ions is possible in the (2) Sigma(+)(v'=1, 2). The analysis of the spectra yields the rotational constants, the spin-rotation coupling constant, and the orb it-rotation coupling constant in the respective electronic states. All angular momentum eigenstates of the (2) Sigma(+)(v'=2) state (and of all higher vibrational states) predissociate. The first eigenstate in the (2) Sigma(+)(v'=1) State that predissociates is the J' = 25/2, R' = 12 state. The lifetime of HBr+ is found to decrease significantly wi th increasing vibrational excitation in the (2) Sigma(+) state. Within the experimental error limits no J dependence of the lifetime is obse rved.