Angular momentum dependent barriers: Possible key to understanding angular distributions for the reactions of fluorine with H2, D2, and HD

摘要

The bending corrected rotating linear model is used to study the angular distributions for the reactions F+H2, F+HD, and F+D2. The calculations are performed using two new surfaces (No. T5 and T5A) that were recently reported by Steckleretal. (Ref. 3). Analysis of the factors determining the shapes of these angular distributions indicates that the angular momentum dependence of the vibrationally adiabatic barriers in the entrance and exit channels plays a central role in determining the characteristics of the vibrational statehyphen;selected, reactive product angular distributions. While the distributions predicted for the reactions F+H2(v=0)rarr;H+HF(vrsquo;=3), F+D2(v=0)rarr;H=DF(vrsquo;=4), and F+DH(v=0)rarr;H+DF(vrsquo;=4) are in good agreement with the high resolution molecular beam studies of these same reactions, the angular distributions predicted for the reaction F+HD(v=0)rarr;D+HF(vrsquo;=3) do now show the forward scattering of products derived from high resolution molecular beam studies. This discrepancy appears to be due to a shortcoming in the T5 and T5a surfaces (i.e., the angular momentum dependent, vibrationally adiabatic barriers in the exit channel are too high in energy to permit forward lsquo;lsquo;resonantrsquo;rsquo; scattering at the low scattering energies corresponding to the experimental studies).