Photochemistry and Non-adiabatic Photodynamics of the HOSO Radical

6 pags., 2 figs.
Hydroxysulfinyl radical (HOSO) is important due to its involvement in climate geoengineering upon SO2 injection and generation of the highly hygroscopic H2SO4. Its photochemical behavior in the upper atmosphere is, however, uncertain. Here we present the ultraviolet-visible photochemistry and photodynamics of this species by simulating the atmospheric conditions with high-level quantum chemistry methods. Photocleavage to HO + SO arises as the major solar-induced channel, with a minor contribution of H + SO2 photoproducts. The efficient generation of SO is relevant due to its reactivity with O3 and the consequent depletion of ozone in the stratosphere.
The project that gave rise to these results received the support of a fellowship for J.C.-G. from “La Caixa” Foundation (ID 100010434); the fellowship code is LCF/BQ/DR20/ 11790027. A.F.-M. is grateful to the Generalitat Valenciana and the European Social Fund for the postdoctoral contract APOSTD/2019/149 and the project GV/2020/226. This work was supported by the Spanish “Ministerio de Ciencia e Innovación (MICINN)” (Project ref CTQ2017-87054-C2-2-P and Unit of Excellence María de Maeztu CEX2019-000919- M). D.R.-S. is grateful to the Spanish MICINN for the “Ramón y Cajal” grant (ref RYC-2015-19234). Computations have been partially conducted at the local QCEXVAL cluster and the Tirant v3 supercluster (University of Valencia).