Dynamics of inelastic H+D2 collisions: Product quantum state distributions at 1.1 and 1.3 eV collision energy

Abstract

We have measured the quantum state distributions of rotationally and vibrationally excited D₂ formed in inelastic H+D₂ collisions at 1.1 and 1.3 eV, under effectively single‐collision conditions. The distributions are derived from highly time‐resolved CARS spectra of D₂. The hydrogen atoms are generated by laser photolysis of HI in an HI/D₂ gas mixture. The D₂ produced in these inelastic collisions is less rotationally and vibrationally excited than the HD produced in reactive H+D₂ collisions at the same energies. The results also show that at 1.3 eV the H+D₂ cross section for producing vibrationally excited D₂ is about one‐half the cross section for producing vibrationally excited HD. The measured D₂ quantum state distributions are in excellent agreement with distributions derived from quasiclassical trajectory calculations on an ab initio H₃ potential surface. However, the quasiclassical trajectory calculated ratio of the vibrationally inelastic nonreactive cross section to the vibrationally nonadiabatic reactive cross section is about 1.5.