Vacuum Ultraviolet Photodissociation Branching Ratios of 12C16O, 13C16O, and 12C18O from 100500 to 102320 cm-1

Lichang Guan; Pan Jiang; Guodong Zhang; Tonghui Yin; Xiaoping Chi; Yu Bai; Min Cheng; Hong Gao

doi:10.1021/acs.jpca.0c08026

Vacuum Ultraviolet Photodissociation Branching Ratios of ¹²C¹⁶O, ¹³C¹⁶O, and ¹²C¹⁸O from 100500 to 102320 cm^-1

J Phys Chem A. 2020 Nov 12;124(45):9382-9391. doi: 10.1021/acs.jpca.0c08026. Epub 2020 Nov 4.

Authors

Lichang Guan^{1

2}, Pan Jiang^{1

2}, Guodong Zhang^{1

2}, Tonghui Yin^{1

2}, Xiaoping Chi^{1

2}, Yu Bai¹, Min Cheng^{1

2}, Hong Gao^{1

2}

Affiliations

¹ Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
² University of Chinese Academy of Sciences, Beijing 100049, China.

PMID: 33146529
DOI: 10.1021/acs.jpca.0c08026

Abstract

The C⁺ ion photofragment spectra and photodissociation branching ratios into the two energetically available channels, C(¹D) + O(³P) and C(³P) + O(³P), have been obtained for the three CO isotopologues, ¹²C¹⁶O, ¹³C¹⁶O, and ¹²C¹⁸O, in the vacuum ultraviolet range 100500-102320 cm^-1. The two vibronic states of ¹Σ⁺ symmetry, F(3dσ) ¹Σ⁺(υ' = 1) and J(4sσ) ¹Σ⁺(υ' = 0), predominantly dissociate into the lowest channel C(³P) + O(³P) through interactions with the repulsive D'¹Σ⁺ state. All three vibronic states of ¹Π symmetry, E'¹Π(υ' = 1, 2) and G(3dπ) ¹Π(υ' = 0), dissociate into both of the channels above. The photodissociation branching ratios into the channel C(¹D) + O(³P) for E'¹Π(υ' = 1, 2) are found to be independent of both the rotational quantum number and e/f parity, while those for G(3dπ) ¹Π(υ' = 0) strongly depend on the rotational quantum number, indicating very different predissociation pathways between the valence states E'¹Π(υ' = 1, 2) and the Rydberg state G(3dπ) ¹Π(υ' = 0). The potential energy curves of CO in the aforementioned energy range and below have recently been well constructed due to a series of interplays between high-resolution spectroscopic studies and theoretical calculations; the photodissociation branching ratios measured in this study can provide further benchmarks for future theoretical investigations which aim to understand the detailed predissociation dynamics of CO.