Strong and selective isotope effect in the vacuum ultraviolet photodissociation branching ratios of carbon monoxide

Rare isotope ( 13 C, 17 O and 18 O) substitutions can substantially change absorption line positions, oscillator strengths and photodissociation rates of carbon monoxide (CO) in the vacuum ultraviolet (VUV) region, which has been well accounted for in recent photochemical models for understanding th...

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Bibliographic Details
Published in:Nature communications 2019-07, Vol.10 (1), p.3175-8, Article 3175
Main Authors: Jiang, Pan, Chi, Xiaoping, Zhu, Qihe, Cheng, Min, Gao, Hong
Format: Article
Language:English
Subjects:
140/125
140/58
639/33/34/4125
639/638/440/94
Carbon 13
Carbon monoxide
Fractionation
Humanities and Social Sciences
Isotope effect
Isotope fractionation
Molecular clouds
multidisciplinary
Oscillator strengths
Photochemicals
Photodissociation
Science
Science (multidisciplinary)
Solar system
Vacuum
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Summary:Rare isotope ( 13 C, 17 O and 18 O) substitutions can substantially change absorption line positions, oscillator strengths and photodissociation rates of carbon monoxide (CO) in the vacuum ultraviolet (VUV) region, which has been well accounted for in recent photochemical models for understanding the large isotopic fractionation effects that are apparent in carbon and oxygen in the solar system and molecular clouds. Here, we demonstrate a strong isotope effect associated with the VUV photodissociation of CO by measuring the branching ratios of 12 C 16 O and 13 C 16 O in the Rydberg 4p(2), 5p(0) and 5s(0) complex region. The measurements show that the quantum yields of electronically excited C atoms in the photodissociation of 13 C 16 O are dramatically different from those of 12 C 16 O, revealing strong isotope effect. This isotope effect strongly depends on specific quantum states of CO being excited, which implies that such effect must be considered in the photochemical models on a state by state basis. Carbon monoxide is the main C and O reservoir in interstellar media, where it undergoes photochemistry. The authors show that isotopic substitution affects not only its absorption. spectrum and photodissociation rates but also the branching ratio, key to understand isotopic. fractionation in the solar system
ISSN:2041-1723
2041-1723
DOI:10.1038/s41467-019-11086-z