State-to-state V-T transfer in HgBr(B ²Σ): A comparison with information theoretic predictions

The collisional relaxation of the vibrational distribution of HgBr(B ²Σ) molecules following initial laser excitation of the v=52 vibrational level has been monitored with observations of the HgBr(B ²Σ-X ²Σ) fluorescence. Spectral simulation methods, developed in previous studies of the nascent vibrational distributions of HgBr (B ²Σ) photofragment molecules, were used for the determination of vibrational state populations. State populations were measured for various degrees of relaxation as the pressure of chaperone molecules, He, Ne, Ar, Xe, and N₂, was progressively increased. An exponential temporal decay characterizes the V-T relaxation of vibrational energy for each buffer gas. A single parameter, the exponential decay time for global V-T relaxation, is all that is required for an information theoretic synthesis of the entire detailed matrix of state-to-state V-T energy transfer probabilities. The computed V-T relaxation of the vibrational distribution, based on the a priori information theoretic predictions is in good agreement with experimental observations.