Experiment study of energy redistribution during collisions of the excited state H₂(1, 7) with LiH

The H₂ was excited to the H₂${\mathrm{X}}^1{\Sigma }_{\mathrm{g}}^{+}$ (v = 1, J = 7) energy level by the stimulated Raman pumping (SRP) technique, and the process of energy redistribution between H₂(1,7) molecule and LiH was studied. The particle population density of H₂(1,7) energy level is obtained by the coherent anti-Stokes Raman scattering (CARS) technique. The particle population density of each rotational level of H₂ (v = 1, J = 7, 5, 3) is analyzed with temperature after the collision between H₂(1,7) molecule and LiH. It is found that the particle population density of each level increases with the increase in temperature after the collision. The time-resolved CARS spectra of each rotational energy level of H₂ (v = 1, J = 7, 5, 3) are analyzed at different temperatures. It is found that a multi-quantum relaxation process with ΔJ = 4 occurs in H₂(1,7) molecule, and the temperature accelerates the relaxation process. The effective lifetime of H₂(1,7) energy level is obtained by plotting the semi-logarithmic plots of the CARS signal intensity and delay time of the level, and observing the law of the effective lifetime change with the temperature. It is found that the effective lifetime of H₂(1,7) energy level shows an obvious decreasing trend with the increase of temperature.