Formation of NO(A 2Σ+,C 2Πr,D 2Σ+) by the ion–ion neutralization reactions of NO+ with C6F5Cl−, C6F5Br−, and C6F−5 at thermal energy

Abstract

The ion-ion neutralization reactions of NO ϩ (X 1 ⌺ ϩ :vЉϭ0) with C 6 F 5 Cl Ϫ , C 6 F 5 Br Ϫ , and C 6 F 5 Ϫ have been spectroscopically studied in the flowing helium afterglow. The NO(A 2 ⌺ ϩ -X 2 ⌸ r ,C 2 ⌸ r -X 2 ⌸ r ,D 2 ⌺ ϩ -X 2 ⌸ r ) emission systems are observed in the NO ϩ /C 6 F 5 Cl Ϫ reaction with the branching ratios of 0.96, 0.017, and 0.028, respectively, while only the NO(A -X) emission system is found in the NO ϩ /C 6 F 5 Br Ϫ and NO ϩ /C 6 F 5 Ϫ reactions. The vibrational and rotational distributions of NO(A,C,D) indicate that only 1%-11% of the excess energy is deposited into vibration and rotation of NO(A,C,D) for all the reactions. In the NO ϩ /C 6 F 5 X Ϫ ͑XϭCl,Br͒ reactions, a major part of the excess energy is expected to be partitioned into the relative translational energy of the neutral products and the vibrational energy of C 6 F 5 X. A comparison of the observed vibrational and rotational distributions with the statistical prior ones indicates that the reaction dynamics is not governed by a simple statistical theory because of the large impact parameter. The excitation mechanism of NO(A,C,D) in the ion-ion neutralization reactions of NO ϩ with C 6 F 5 X Ϫ ͑XϭF,Cl,Br,CF 3 ͒ and C 6 F 5 Ϫ is discussed.

3 Optical studies of ion–molecule reactions

“…Recently, Tsuji et al 93,[103][104][105][106] have performed an extensive series of experiments in which emissions following ion-ion recombination have been analysed. This work represents a significant extension to the early work of Smith et al 107 who studied the NO 1 1 NO 2 2 recombination reaction and complements the recent information obtained on DR processes (see section 3.2.1.2).…”