HOD在真空紫外光解离中的强同位素效应：太阳星云D/H同位素非均一性的一个可能起源。
Strong isotope effect in the VUV photodissociation of HOD: A possible origin of D/H isotope heterogeneity in the solar nebula.
作者信息
Luo Zijie, Zhao Yarui, Chen Zhichao, Chang Yao, Zhang Su-E, Wu Yucheng, Yang Jiayue, Cheng Yi, Che Li, Wu Guorong, Xie Daiqian, Yang Xueming, Yuan Kaijun
机构信息
Department of Physics, School of Science, Dalian Maritime University, 1 Linghai Road, Dalian, Liaoning 116026, China.
State Key Laboratory of Molecular Reaction Dynamics and Dalian Coherent Light Source, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, China.
出版信息
Sci Adv. 2021 Jul 21;7(30). doi: 10.1126/sciadv.abg7775. Print 2021 Jul.
The deuterium versus hydrogen (D/H) isotopic ratios are important to understand the source of water on Earth and other terrestrial planets. However, the determinations of D/H ratios suggest a hydrogen isotopic diversity in the planetary objects of the solar system. Photochemistry has been suggested as one source of this isotope heterogeneity. Here, we have revealed the photodissociation features of the water isotopologue (HOD) at λ = 120.8 to 121.7 nm. The results show different quantum state populations of OH and OD fragments from HOD photodissociation, suggesting strong isotope effect. The branching ratios of H + OD and D + OH channels display large isotopic fractionation, with ratios of 0.70 ± 0.10 at 121.08 nm and 0.49 ± 0.10 at 121.6 nm. Because water is abundant in the solar nebula, photodissociation of HOD should be an alternative source of the D/H isotope heterogeneity. This isotope effect must be considered in the photochemical models.
氘与氢（D/H）的同位素比率对于理解地球及其他类地行星上的水源至关重要。然而，D/H比率的测定表明太阳系行星天体中存在氢同位素多样性。光化学被认为是这种同位素异质性的一个来源。在此，我们揭示了水同位素分子（HOD）在λ = 120.8至121.7纳米处的光解离特征。结果显示，HOD光解离产生的OH和OD碎片具有不同的量子态分布，表明存在强烈的同位素效应。H + OD和D + OH通道的分支比呈现出较大的同位素分馏，在121.08纳米处的比率为0.70±0.10，在121.6纳米处为0.49±？0.10（此处原文似乎有误，推测可能是0.49 ± 0.10 ）。由于水在太阳星云中含量丰富，HOD的光解离应该是D/H同位素异质性的另一个来源。在光化学模型中必须考虑这种同位素效应。
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