Complex angular momentum theory of state-to state integral cross sections: resonance effects in the F+HD->HF(v'=3)+D reaction

TL;DR

This paper applies complex angular momentum theory and the ICS_Regge computational tool to analyze resonance effects in the F+HD->HF+D reaction, revealing detailed resonance patterns and their impact on integral cross sections.

Contribution

It is the first detailed analysis of resonance patterns in this reaction using Regge pole theory and the ICS_Regge code, linking complex energies to observable cross section features.

Findings

Identification of multiple resonances affecting cross sections

Observation of Fano and sinusoidal resonance shapes

Correlation between Regge poles and resonance features

Abstract

State-to-state reactive integral cross sections (ICS) are often affected by quantum mechanical resonances, especially at relatively low energies. An ICS is usually obtained by summing partial waves at a given value of energy. For this reason, the knowledge of pole positions and residues in the complex energy plane is not sufficient for a quantitative description of the patterns produced by a resonance. Such description is available in terms of the poles of an S-matrix element in the complex plane of the total angular momentum. The approach was recently implemented in a computer code ICS_Regge, available in the public domain [Comp. Phys. Comm. 185 (2014) 2127]. In this paper, we employ the ICS Regge package to analyse in detail, for the first time, the resonance patterns predicted for the integral cross sections (ICS) of the benchmark F+HD->HF(v'=3)+D reaction. The v = 0, j = 0, Omega = 0 -> v' = 3, j'= 0,1,2, and Omega' = 0,1,2 transitions are studied for collision energies from 58.54 to 197.54 meV. For these energies, we find several resonances, whose contributions to the ICS vary from symmetric and asymmetric Fano shapes to smooth sinusoidal Regge oscillations. Complex energies of metastable states and Regge pole positions and residues are found by Pad /'e reconstruction of the scattering matrix elements. Accuracy of the ICS Regge code, relation between complex energies and Regge poles, various types of Regge trajectories, and the origin of the J-shifting approximation are also discussed.