Three body photodissociation of the water molecule and its implications for prebiotic oxygen production.
basic_science · Level V
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- Record sourced from PubMed, PMID 33931653.
- Also identified by DOI 10.1038/s41467-021-22824-7 and PMC identifier 8087761.
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Abstract
The provenance of oxygen on the Earth and other planets in the Solar System is a fundamental issue. It has been widely accepted that the only prebiotic pathway to produce oxygen in the Earth's primitive atmosphere was via vacuum ultraviolet (VUV) photodissociation of CO<sub>2</sub> and subsequent two O atom recombination. Here, we provide experimental evidence of three-body dissociation (TBD) of H<sub>2</sub>O to produce O atoms in both <sup>1</sup>D and <sup>3</sup>P states upon VUV excitation using a tunable VUV free electron laser. Experimental results show that the TBD is the dominant pathway in the VUV H<sub>2</sub>O photochemistry at wavelengths between 90 and 107.4 nm. The relative abundance of water in the interstellar space with its exposure to the intense VUV radiation suggests that the TBD of H<sub>2</sub>O and subsequent O atom recombination should be an important prebiotic O<sub>2</sub>-production, which may need to be incorporated into interstellar photochemical models.