Open AccessStrong isotope effect in the VUV photodissociation of HOD: A possible origin of D/H isotope heterogeneity in the solar nebula
Author(s) -
Zhihan Luo,
Yarui Zhao,
Zhichao Chen,
Yao Chang,
Su'e Zhang,
Yucheng Wu,
Ji Yang,
Yi Cheng,
Li Che,
Guorong Wu,
Daiqian Xie,
Xueming Yang,
Kaijun Yuan
Publication year - 2021
Publication title -
science advances
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.928
H-Index - 146
ISSN - 2375-2548
DOI - 10.1126/sciadv.abg7775
Subject(s) - isotope , photodissociation , nebula , formation and evolution of the solar system , physics , astrobiology , astrophysics , kinetic isotope effect , astronomy , chemistry , atomic physics , solar system , deuterium , photochemistry , nuclear physics , stars
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.