Issue 31, 2010

Dynamics of the I + HI → IH + I reaction: application of nearside–farside, local angular momentum and resummation theories using the Fuller and Hatchell decompositions

Abstract

The differential cross section (DCS) for the I + HI(vi = 0, ji = 0) → IH(vf = 0, jf = 2) + I reaction at a translational energy of 21.3 meV is studied, where vi, ji and vf, jf are vibrational, rotational quantum numbers for the initial and final states respectively. We apply new theoretical developments (since 2001) in nearside–farside (NF) theory to provide insights into intricate oscillatory structures in its DCS. It is shown that a simple physically-meaningful parameterization of the scattering (S) matrix, using a background Gaussian term plus a single Regge pole and a quadratic phase, can reproduce, in the forward and sideward directions, the intricate angular scattering obtained from numerical S matrix elements computed from a quantum Born-Oppenheimer–Centrifugal-Sudden scattering technique. This encouraging result suggests that many S matrix elements obtained from computer-intensive calculations can be parameterized in a similar physically-meaningful way. The manner in which the full and NF DCSs change when the Regge pole becomes progressively less important compared to the Gaussian term is also investigated. We report the first application to reactive scattering of the Hatchell NF decomposition, including resummations of the Legendre partial wave series for the scattering amplitude. The Hatchell NF resummed DCSs are compared with the corresponding Fuller NF resummed DCSs for resummation orders of r = 0, 1, 2 and 3. We find that the Fuller NF decomposition always provides a better physical interpretation of the angular scattering. Resummation usually cleans the NF DCSs of unphysical oscillations, especially in the farside (F) DCSs, with the greatest cleaning effect on going from no resummation (r = 0) to first order resummation (r = 1). Identities are derived which relate the Fuller and Hatchell NF subamplitudes for resummation orders, r > 0, to the NF unresummed subamplitudes, r = 0. These identities help us understand the origin of unexpected peaks, which sometimes appear in NF resummed DCSs, together with a simple procedure to remove them. We report Local Angular Momentum (LAM) and DCS × LAM (CLAM) analyses of the angular scattering for r = 0 and r = 1 using the Fuller NF decomposition. The LAM and CLAM analyses provide complementary (yet consistent) information to that obtained from the NF resummed DCSs. It is shown that the “l window representation”, as used to analyse elastic scattering in the presence of strong absorption, is a special case of the general resummation theory developed in this paper.

Graphical abstract: Dynamics of the I + HI → IH + I reaction: application of nearside–farside, local angular momentum and resummation theories using the Fuller and Hatchell decompositions

Article information

Article type
Paper
Submitted
17 Feb 2010
Accepted
13 Apr 2010
First published
25 May 2010

Phys. Chem. Chem. Phys., 2010,12, 8772-8791

Dynamics of the I + HI → IH + I reaction: application of nearside–farside, local angular momentum and resummation theories using the Fuller and Hatchell decompositions

A. J. Totenhofer, C. Noli and J. N. L. Connor, Phys. Chem. Chem. Phys., 2010, 12, 8772 DOI: 10.1039/C003374J

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements