State selected ion–molecule reactions by a TESICO technique. V. N2+(v)+Ar→N2+Ar+

Abstract

Charge transferreactions N2 +(v)+Ar→Ar++N2 (1) have been studied by selecting the vibrational states of N2 + using the threshold electron–secondary ion coincidence (TESICO) technique. Relative cross sections σ(v) for the individual vibrational statesv = 0–3 have been determined at three collision energies, 0.3, 1.5, and 11.8 eV. Results show that Reaction (1), which is endoergic for v = 0, is considerably enhanced by the vibrational excitation of N2 + at all collision energies. While excitation of one vibrational quantum enhances the cross section substantially, excitation of additional quanta further increases the cross section up to v = 3. The ratios σ(2)/σ(1) and σ(3)/σ(2) are, however, much smaller than σ(1)/σ(0) and are significantly larger at the highest collision energy than at the other two collision energies. These results are discussed in conjunction with the calculated results based on the simple two‐state theory of Rapp and Francis and the Franck–Condon factors.