A deperturbation analysis of the B-3 Sigma(-)(u)(v'=0-6) and the B''(3)Pi(u)(v'=2-12) states of S-2

Laser-induced fluorescence spectra of S-32(2) have been obtained, covering upsilon'=0-6 of the B (3) Sigma(u)(-)-X (3) Sigma(g)(-) transition and upsilon'=2-12 of the B ''(3) Pi(u)-X(3) Sigma(g)(-) transition, using static cell and supersonic free jet techniques. The spectra include transitions to the previously unseen B ''(3) Pi(2,u) components. Analysis of the many perturbations between the two upper electronic states has been carried out using a Hamiltonian matrix including- all the B and B '' states simultaneously rather than deperturbing individual pairs of vibronic states. This takes into account longer range interactions and gives deperturbed molecular constants that vary smoothly with vibrational state. Our model for the B ''upsilon'=2-12 and B upsilon'=0-6 levels covering J up to 100 can fit all 3320 observed transitions with an average error of 0.064 cm(-1). The widely ranging fluorescence lifetimes of the B '' state vibronic levels provide independent information about thr state mixing and confirm the model, since the observed B ''-X fluorescence arises-almost entirely via this mixing. However, lifetime measurements of the newly observed Omega=2 components of the B '' state showed little variation in lifetimes, about an average of 4.2+/-0.4 mu s. This indicates a small intrinsic B ''-X transition strength as the Omega=2 components are essentially not mixed with the B state. A model for the perturbation parameters is developed,- based on Franck-Condon-factors between the two states. The magnitude of the perturbations and transition moments are discussed in relation to the electronic configurations of the B and B '' states. (C) 1996 American Institute of Physics.