The orientation dependence of CN(B) radical formation in the reaction of the Ar(3P) atoms with oriented CDjCN 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.

A newly developed Doppler-selected time-of-flight ͑a 3D͒ method was applied to map out for the first time the vibrational-specific angular distributions of the DCN product from the title reaction. A tentative vibrational assignment was given for the observed structures. It was found that the nascent DCN is formed with substantial excitations in both C-D stretch and DCN bend modes. While the pure C-D stretch and those associated with low bend excitations are predominantly backward scattered, the highly excited DCN in both modes also exhibit a substantial forward scattered component in the angular distribution.

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An alignment dependence of the NH2(A-X) chemiluminescence was studied in the reaction of the aligned NH3 molecules and the metastable Ar(3P) atoms by using hexapole state selection. The NH2 emission intensities were analyzed by a hard-sphere model for the NH3 molecule. The ratio of the emission cross sections for the head-on attack and the side-on attack was found to be crh/

The formation ratio of the two spin-orbit states, 3P0 / 3P2, of the metastable argon, Ar*, was investigated by the glow discharge of a pulsed Ar supersonic beam. The 3P0 / 3P2 ratio decreased with the increase of the glow discharge potential Vg, by which the electron bombardment initiates the discharge. The observed Vg-dependence clearly showed an inverse behavior against Vg as compared with that in the conventional electron impact by low beam densities.