Fig: Dalian Coherent Light Source revealing strong isotope effects in water photochemistry.
There 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 Because water is one of the most adundant 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.
Zijie Luo et al, Strong isotope effect in the VUV photodissociation of HOD: A possible origin of D/H isotope heterogeneity in the solar nebula, Science Advances (2021). DOI: 10.1126/sciadv.abg7775