### Abstract

Comparisons are presented of experimental and theoretical studies of the rotationally inelastic scattering of CD_{3} 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 CD_{3} 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 CD_{3} 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 CD_{3} 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 CD_{3}-H_{2} and CD_{3}-D_{2} collisions. Further comparisons are drawn between the CD_{3}-D_{2} scattering and results for CD_{3}-He presented in our recent paper [O. Tkáč, 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.

Original language | English |
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Article number | 204318 |

Journal | Journal of Chemical Physics |

Volume | 140 |

Issue number | 20 |

DOIs | |

Publication status | Published - 28 May 2014 |

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### ASJC Scopus subject areas

- Physics and Astronomy(all)
- Physical and Theoretical Chemistry

### Cite this

_{2}and D

_{2}.

*Journal of Chemical Physics*,

*140*(20), [204318]. https://doi.org/10.1063/1.4879618