Orientation-dependent CF₃ emission observed in the Ar(³P) + CF₃H → CF₃* (1E′, 2A″₂) + H + Ar reaction

The orientation-dependent CF3 emission in the visible region observed in the Ar(3P) + CF3H reaction was investigated. The Legendre polynomial and Engel-Levine function expansions were applied to obtain an orientational opacity function, in which the lowest six terms of the Legendre series were found to be important to reproduce the observed orientational dependence. In both cases, these opacity functions reveal three reactive sites. The most favorable one is the attack of the Ar(3P) atom at the CF3 group in the collinear approach and the second one correlates with the direct approach to the F atom. The least favorable site is centered at around 140° in the region of H atom attack. There is a cone of small reactivity in the collinear direction at the H-end attack. Although the exchange interaction cannot completely explain the relative reactivity at each reaction site, the shape of the opacity function was attributed to the exchange interaction between the 6a1 molecular orbital of CF3H and the 3p empty core orbital of Ar(3P). © 1992.