Molecular beam studies of the F+H2 reaction

The dynamics of the F+H2 reaction have been investigated in a high resolution crossed molecular beam study. Differential cross sections and kinetic energy distributions were obtained for each HF vibrational state. The v=1 and v=2 states were predominantly backward scattered, but substantial forward scattering was observed for HF (v=3) over the range of collision energies accessible in our apparatus, from 0.7 to 3.4 kcal/mol. The results strongly suggest that dynamical resonances play a significant role in the reaction dynamics of F+H2 and that resonance effects are most prominent in the v=3 product channel. Quantal reactive scattering calculations on F+H2 predict that the v=2 channel should be most strongly affected by resonances. This discrepancy is attributed to inadequacies in the potential energy surface used in the calculations, and several modifications to the surface are proposed based on the experimental results. Other features of the reaction are also discussed, including the integrated partial cross sections, the effect of H2 rotation, and the reactivity of F(2P1/2).