State selected ionndash;molecule reactions by a TESICO technique. VIII. Vibronichyphen;state dependence of the cross sections in the reaction NO+(athinsp;3Sgr;+,thinsp;v;bthinsp;3Pgr;,thinsp;v)+Arthinsp;rarr;thinsp;NO+Ar+

摘要

Charge transfer reactions NO++Arthinsp;rarr;thinsp;Ar++NO (1) have been studied by selecting the vibronic states of NO+using the threshold electronndash;secondary ion coincidence (TESICO) technique. The vibronic states selected wereathinsp;3Sgr;+,v=0ndash;5 andbthinsp;3Pgr;,v=0, for each of which the relative cross sections have been determined at two collision energies 1.4 and 5.8 eV. The cross section for theathinsp;3Sgr;+state has been found to show a resonancelike enhancement atv=2. This feature is reproduced fairly well by the simple twohyphen;state theory of Rapp and Francis combined with the consideration of the Franckndash;Condon factors. However, a closer comparison of the theoretical and experimental results over the entire range ofvreveals that the reaction cross sections for theathinsp;3Sgr;+reactant ion state consist of two components, one in which the vibrationalhyphen;state dependence is determined simply by the energy defects and Franckndash;Condon factors, and the other in which the vibrationalhyphen;state dependence cannot be interpreted by those factors. The cross section for thebthinsp;3Pgr;,v=0 state has been found to be much smaller than those for the exoergic reactions of theathinsp;3Sgr;+state (v=1ndash;5). This has been attributed to the difference in the nature of the molecular orbitals that play primary roles in theathinsp;3Sgr;+andbthinsp;3Pgr; reactions.