Differential and integral cross sections for the rotationally inelastic scattering of methyl radicals with H-2 and D-2

Ondrej Tkac*, Qianli Ma, Cassandra A. Rusher, Stuart J. Greaves, Andrew J. Orr-Ewing, Paul J. Dagdigian

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

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Comparisons are presented of experimental and theoretical studies of the rotationally inelastic scattering of CD3 radicals with H-2 and D-2 collision partners at respective collision energies of 680 +/- 75 and 640 +/- 60 cm(-1). Close-coupling quantum-mechanical calculations performed using a newly constructed ab initio potential energy surface (PES) provide initial-to-final CD3 rotational level (n, k -> n', k') integral and differential cross sections (ICSs and DCSs). The DCSs are compared with crossed molecular beam and velocity map imaging measurements of angular scattering distributions, which serve as a critical test of the accuracy of the new PES. In general, there is very good agreement between the experimental measurements and the calculations. The DCSs for CD3 scattering from both H-2 and D-2 peak in the forward hemisphere for n' = 2-4 and shift more to sideways and backward scattering for n' = 5. For n' = 6-8, the DCSs are dominated by backward scattering. DCSs for a particular CD3 n -> n' transition have a similar angular dependence with either D-2 or H-2 as collision partner. Any differences between DCSs or ICSs can be attributed to mass effects because the PES is unchanged for CD3-H-2 and CD3-D-2 collisions. Further comparisons are drawn between the CD3-D-2 scattering and results for CD3-He presented in our recent paper [O. Tkac, A. G. Sage, S. J. Greaves, A. J. Orr-Ewing, P. J. Dagdigian, Q. Ma, and M. H. Alexander, Chem. Sci. 4, 4199 (2013)]. These systems have the same reduced mass, but are governed by different PESs. (C) 2014 AIP Publishing LLC.

Original languageEnglish
Article number204318
Number of pages12
JournalJournal of Chemical Physics
Issue number20
Publication statusPublished - 30 May 2014

Bibliographical note

Accepted 13/05/2014


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