T–V energy transfer and the exchange reaction of H(D)+HF at 2.2(2.1) eV: Vibrational state distributions by time and wavelength resolved infrared fluorescence

Abstract

The product state distributions for hot atom collisions of H(D)+HF are measured by the laser photolysis–infrared emission technique. The vibrational distribution of the HF T–V transfer process and exchange reaction product at 2.2 eV is 0.81±0.08, 0.16±0.02, and 0.03±0.01 corresponding to v=1–3, respectively. The HF and DF distritubions resulting from D+HF collisions at 2.1 eV are 0.65±0.09, 0.25±0.05, and 0.10±0.02 for HF(v=1–3) and 0.55±0.09, 0.25±0.04, 0.14±0.02, and 0.06±0.01 for DF(v=1–4). It is found that H atoms are 3.0 times more efficient than D atoms at exciting HF vibrations for the same kinetic energy. Although the vibrational distributions are similar, the D+HF T–V channel deposits approximately two times as much energy in the HF molecules as the vibrational exchange channel leaves in the DF molecules. The results are compared to recent three-dimensional quasiclassical trajectory calculations and classical infinite-order-sudden calculations (accompanying paper) and are also considered in light of some simple models. The agreement between experiment and theory is excellent. The theoretical results show that significantly different mechanisms are resonsible for T–V energy transfer on the reactive and unreactive portions of the potential energy surface.