Deuterium isotope effect on the orientation dependence of CN(B) radical formation in the reaction of Ar(³P) with CD₃CN

The orientation dependence of CN(B) radical formation in the reaction of the Ar(³P) atoms with oriented CD₃CN molecules by use of a hexapole electrostatic field was studied, and the dissimilar orientational anisotropy as compared with that for the reaction with the oriented CH₃CN molecules was found. This difference in stereoanisotropy suggests that the CN(B) formation has at least two reaction processes. These processes are relevant to anisotropic and isotropic molecular orbitals of acetonitrile at the stage of energy transfer from the Ar(³P) atoms. The emission spectra of the CN(B) radicals for both reactions with randomly oriented acetonitrile were observed to investigate the relationship between the vibrational excitation of the CN(B) radical and branching either to CN(B) formation or to hydrogen atomization.