Semiclassical angular scattering in the F+H2→HF+H reaction: Regge pole analysis using the Padé approximation

We apply the complex angular momentum analysis to study state-selective forward scattering in the F+H2 reaction. The scattering matrix calculated by Castillo et al. is used. The S-matrix element is analytically continued into the complex plane of the total angular momentum with the help of the Padé approximation. Resonance (Regge) poles are identified and their residues evaluated. The semiclassical optical model is corrected to account for finite lifeangles of leading resonances. For chosen transitions, the forward scattering enhancement is shown to be a resonance effect due to the decay of a Regge state with angular life of about 32°.