A single resonance Regge pole dominates the forward-angle scattering of the state-to-state F + H2 → FH + H reaction at Etrans = 62.09 meV

Chengkui Xiahou; J N L Connor; Dario De Fazio; Dmitri Sokolovski

doi:10.1039/d3cp04734b

A single resonance Regge pole dominates the forward-angle scattering of the state-to-state F + H₂ → FH + H reaction at E_trans = 62.09 meV

Phys Chem Chem Phys. 2024 Jan 24;26(4):3647-3666. doi: 10.1039/d3cp04734b.

Authors

Chengkui Xiahou¹, J N L Connor², Dario De Fazio³, Dmitri Sokolovski^{4

5}

Affiliations

¹ School of Pharmacy, Qilu Medical University, Zibo Economic Zone, Zibo City 255300, Shandong, People's Republic of China.
² Department of Chemistry, The University of Manchester, Manchester M13 9PL, UK. j.n.l.connor@manchester.ac.uk.
³ Istituto di Struttura della Materia-Consiglio Nazionale delle Ricerche, 00016 Roma, Italy.
⁴ Department of Physical Chemistry, University of the Basque Country, 48940 Leioa, Bizkaia, Spain.
⁵ IKERBASQUE, Basque Foundation for Science, 48011, Bilbao, Spain.

PMID: 38224460
DOI: 10.1039/d3cp04734b

Abstract

The aim of the present paper is to bring clarity, through simplicity, to the important and long-standing problem: does a resonance contribute to the forward-angle scattering of the F + H₂ reaction? We reduce the problem to its essentials and present a well-defined, yet rigorous and unambiguous, investigation of structure in the differential cross sections (DCSs) of the following three state-to-state reactions at a translational energy of 62.09 meV: F + H₂(v_i = 0, j_i = 0, m_i = 0) → FH(v_f = 3, j_f = 0, 1, 2, m_f = 0) + H, where v_i, j_i, m_i and v_f, j_f, m_f are the initial and final vibrational, rotational and helicity quantum numbers respectively. Firstly, we carry out quantum-scattering calculations for the Fu-Xu-Zhang potential energy surface, obtaining accurate numerical scattering matrix elements for indistinguishable H₂. The calculations use a time-independent method, with hyperspherical coordinates and an enhanced Numerov method. Secondly, the following theoretical techniques are employed to analyse structures in the DCSs: (a) full and Nearside-Farside (NF) partial wave series (PWS) and local angular momentum theory, including resummations of the full PWS up to second order. (b) The recently introduced "CoroGlo" test, which lets us distinguish between glory and corona scattering at forward angles for a Legendre PWS. (c) Six asymptotic (semiclassical) forward-angle glory theories and three asymptotic farside rainbow theories, valid for rainbows at sideward-scattering angles. (d) Complex angular momentum (CAM) theories of forward and backward scattering, with the Regge pole positions and residues computed by Thiele rational interpolation. Thirdly, our conclusions for the three PWS DCSs are: (a) the forward-angle peaks arise from glory scattering. (b) A broad (hidden) farside rainbow is present at sideward angles. (c) A single Regge pole contributes to the DCS across the whole angular range, being most prominent at forward angles. This proves that a resonance contributes to the DCSs for the three transitions. (d) The diffraction oscillations in the DCSs arise from NF interference, in particular, interference between the Regge pole and direct subamplitudes.