Branching ratios among three product channels of the dissociative recombination reaction in Ar-2(+)

Measurements of the pressure dependence of the dissociative recombination ( DR) reaction transition of Ar-2(+) (v = 0) to the 3d'[3/2] J = 1, the 4p[1/ 2] J = 1, and the 4p'[1/2] J=0 final product states of the argon atom have been done in an argon glow discharge using time-of-flight spectroscopy. The velocity of these final-product-state atoms is close to the most probable velocity (approximate to 750 m/sec) of the argon atoms in the discharge, so that their distributions appear as spikes within the Boltzman distribution . The narrow velocity distributions of these DR product atoms suggests that the velocity of the Ar-2(+) ion parents, which are created by associative ionization reactions, were very subthermal and nearly zero. One collision w ith an Ar atom would cause the Ar-2(+) ion to gain, on the average, 47% of the velocity of that Ar atom, which would broaden the DR product distributi on so that the peak would not be observable. However, if the inn parent dis sociates before any collision, the DR distribution will be narrow and thus observable. Determining, experimentally, the pressure at which the narrow p eaks broaden and by calculating the collision time corresponding to that pr essure, the lifetimes of the DR transitions have been estimated.