Researchers found that when a hydrogen-deuterium water molecule is broken apart by light, it doesn’t always break the same way. These differences might help explain why the ratio of hydrogen to deuterium varies across the solar system.
Recently, a research group led by Prof. YUAN Kaijun and Prof. YANG Xueming from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences revealed strong isotope effects in photodissociation of the water isotopologue (HOD) using the Dalian Coherent Light Source.
Their findings were published in Science Advances on July 21, 2021.
“Our experimental results illustrate dramatically different quantum state population distributions of OH and OD fragments from HOD photodissociation. The branching ratios of the H+OD and D+OH channels display large wavelength-dependent isotopic fractionation,” said Prof. YUAN.
Because water is one of the most abundant species in the solar nebula, photodissociation of water and its isotopologue by solar vacuum ultraviolet photons may be an alternative source of the D/H isotope heterogeneity, and this effect must be considered in photochemical models.
The photochemical processes identified in this work may vary the D/H isotopic ratios in the inner and outer regions, and/or in different periods of the solar nebula, which may cause the D/H isotope heterogeneity in the solar system.
Reference: “Strong isotope effect in the VUV photodissociation of HOD: A possible origin of D/H isotope heterogeneity in the solar nebula” by Zijie Luo, Yarui Zhao, Zhichao Chen, Yao Chang, Su-e Zhang, Yucheng Wu, Jiayue Yang, Yi Cheng, Li Che, Guorong Wu, Daiqian Xie, Xueming Yang and Kaijun Yuan, 21 July 2021, Science Advances.
DOI: 10.1126/sciadv.abg7775
This research was supported by the Strategic Priority Research Program of the Chinese Academy of Sciences, Chemical Dynamics Research Center, and the National Natural Science Foundation of China.
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