Exponential gap relation and the rotational inelasticity of H₂---M systems

Abstract

Previously published values of state-to-state integral inelastic cross sections for the H₂(J_i)—M (M=H, He, Li, Li⁺, H₂, CO₂) systems are fitted to the exponential gap relation for the rotational inelastic process to obtain the C value that reflects the magnitudes of relative cross sections. While the vibration of the rotor seems to have little influence, the C value is shown to decrease dramatically with increase in initial collision energy T_i, ΔC/ΔT_i being larger at lower T_i for all systems analysed, in accord with the prediction of the surprisal synthesis of Procaccia and Levine. For the only case of H₂(J_i)-Li⁺ for which results are available for several J_i, C decreases with increase in J_i or J_i(J_i + 1)). The C value predicted by Procaccia and Levine for H₂=M systems falls within the range of C values calculated for the various collision partners. However, there is a noticeable change in C (albeit within a factor of two) with change in M, indicating that dynamical factors do play an important role in rotational inelastic processes.