Dynamics of Chemical and Charge-Transfer Reactions of Molecular Dications: III.Beam Scattering and Total Cross Section Data for Processes in the Systems CO_2~(2+) + D_2

摘要

Chemical reactions and charge-transfer processes in the system CO_2~(2+) + D_2 were investigated in crossedbeam scatering experiments.Theoretical calculations of stationary points on the dication potential energy surface (CO_2D_2)~(2+) were carried out to complement the experiments.The main ion products identified were CO_2D~+,COD,CO_2~+,CO~+,and O~+.The relative cross sections for reactions with D_2 (H_2) were in the ratio CO_2~+:COD~+:CO_2D~+ = 100:10:1 and were almost independent of the collision enery over the range 0.5-4 eV (center-of-mass,C.M.).The chemical product CO_2D~+ was formed in a nondissociative chemical reaction leading to CO_2D~+ + D~+ through two channels that released different amounts of translational energy via decomposition of intermediates (CO_2D_2)~(2+); the high translational energy release channel (peak value at 4 eV) is consistent with the energetics of formation of a D-C-bonded isomer DCO_2~+,which dissociates further to form DCO~+ + O.The charge-transfer product CO_2~+ is formed prevailingly in the excited states A and B; a small amount is also formed by further dissociation of the product CO_2D~+ (formed in the low translational energy relase channel,presumably in an excited state) to CO_2~+ + D.The product CO~+ results from two different processes: from charge transfer leading to CO_2~+(C~2 #SIGMA#_g~+) + D_2~+ and predissociation of the C state to CO~+(X~2#SIGMA#~+) + O(~3P) and from spontaneous dissociation of the projectile CO_2~(2+) (vibrationally excited to its predissociation barrier) to CO~+ + O~+.