Experimental Investigations of Vibration-Vibration Energy Transfer in HBr(X-1 sigma(+)v''=5, 6)-H-2 Collisions

This study experientally investigated the vibration-vibration (V-V) energy transfer process in the HBr-H-2 mixing system (molar ratio: 0.4; total pressure: 500 Pa) at room temperature (T = 295 K). Degenerate stimulated hyper-Raman pumping was used to excite HBr molecules to the X-1 sigma(+)v '' = 5, 6 excited states, and the population distribution of the ro-vibrational states of the H-2 molecules following collision was determined by coherent anti-stokes raman scattering (CARS) Spectroscopy. The scanning coherent anti-stokes raman scattering (CARS) spectra revealed that the H-2 molecules were populated at vibrational rotation energy levels of v = 1, 2 after colliding with the HBr (v '' = 5, 6). The ratio of the population of each vibrational rotation energy level of the H-2 molecules was obtained through simple dynamic model analysis and the relative intensity ratio of the coherent anti-stokes raman scattering (CARS) spectrum. The analysis of the Boltzmann distribution and relative intensity ratio of the H-2 molecule v = 0 in thermal equilibrium demonstrated the population of the v = 1, 2 vibrational rotation energy level after the collision of the H-2 molecule with HBr (v '' = 5, 6). After colliding with HBr (v '' = 6), the ratio of the number of particles of the H-2 (1, 3) and (2, 3) levels xi = n(1)/n(2) had multiple values, and the theoretical formula was fitted by the time-resolved coherent anti-stokes raman scattering (CARS) spectral profile. The actual population ratio was 1.76. The time evolution profile of the population number on the vibrational excited HBr (v '' <= 5, 6) after colliding with the H-2 molecules was measured, and two-quantum near resonance in the HBr (v '' = 5, 6) + H-2 system was observed. Thus, direct evidence that the two-quantum relaxation process occurred was provided.