The N + Formation Mechanism of Vibrationally Selected N 2 O + Ions in the C 2 Σ + State: A TPEPICO Imaging Study

The N-NO bond fission of N O (C Σ ) ions can produce two major fragment ions, NO or N . In contrast to the dominant NO fragment ion, the N formation mechanism remains unclear to date. Here, dissociative photoionization of N O via the C Σ ionic state has been reinvestigated using a combined approach...

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Published in:The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory Molecules, spectroscopy, kinetics, environment, & general theory, 2024-05
Main Authors: Chen, Yan, Wu, Xiangkun, Zhou, Xiaoguo, Yang, Xinlang, Dai, Xinhua, Liu, Shilin
Format: Article
Language:English
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Summary:The N-NO bond fission of N O (C Σ ) ions can produce two major fragment ions, NO or N . In contrast to the dominant NO fragment ion, the N formation mechanism remains unclear to date. Here, dissociative photoionization of N O via the C Σ ionic state has been reinvestigated using a combined approach of threshold photoelectron-photoion coincidence (TPEPICO) velocity imaging and quantum chemical calculations. Accompanying the N ( P) formation, the NO(X Π) neutral fragment with low and high vi-rotational distributions was identified, based on the N speed and angular distributions derived from the TPEPICO images. In particular, the excitation of the symmetric stretching ν mode promotes the formation of high rotational components, while the asymmetric stretching ν mode shows the exact opposite effect. According to our calculated multistate potential energy surfaces, intersystem crossing from C Σ to 1 Π exclusively provides feasible decomposition pathways to produce the N fragment. In a slightly bent geometry, spin-orbit couplings between C Σ and two substates of 1 Π, 1 A' or 1 A″, play a crucial role in the N formation from vibrationally selected N O (C Σ ) ions. The mechanism also provides new insights into the charge transfer reaction of N + NO → N + NO .
ISSN:1089-5639
1520-5215
DOI:10.1021/acs.jpca.4c00494