TITLE:

Experimental determination of the specific opacity function for the Ba+HI ® BaI(v=0)+H reaction

AUTHORS:

Vaccaro, P.H.; Tsekouras, A.A.; Daqing Zhao; Leach, C.A.; Zare, R.N.; Dept. of Chem., Stanford Univ., CA, USA

PUBLICATION:

Journal of Chemical Physics, vol.96, no.4, p. 2786-98, 15 Feb. 1992 42 Refs.

ABSTRACT:

Through the use of laser-induced fluorescence spectroscopy, product rotational population distributions were recorded for the Ba(¹S₀) + HI(X¹Ó⁺) ® BaI(X²Ó⁺, v=0)+H(²S_1/2) reaction under well-defined, crossed-beam conditions. In this kinematically constrained reaction, orbital angular momentum of the reagents L_reag is channeled almost exclusively into rotational angular momentum of the products J_prod. Consequently, ¦J_prod¦ = ì v_rel b, where ì is the reduced mass of the reactants, v_rel is their relative velocity, and b is the impact parameter of the reactive collision. For relative velocity distributions with mean values ranging from 860 to 1000 m s^-1, the BaI v=0 rotational distributions were found to peak sharply at high J values (~420). Nonlinear least-squares analysis showed the specific opacity function (impact parameter distribution) for the formation of vibrationless BaI product to be exceptionally narrow (approximately 0.3 A FWHM) with a pronounced maximum at the highest energetically allowed impact parameter approximately 4.5 A.