Criegee intermediate-hydrogen sulfide chemistry at the air/water interface

We carry out Born-Oppenheimer molecular dynamic simulations to show that the reaction between the smallest Criegee intermediate, CH₂OO, and hydrogen sulfide (H₂S) at the air/water interface can be observed within few picoseconds. The reaction follows both concerted and stepwise mechanisms with former being the dominant reaction pathway. The concerted reaction proceeds with or without the involvement of one or two nearby water molecules. An important implication of the simulation results is that the Criegee-H₂S reaction can provide a novel non-photochemical pathway for the formation of a C-S linkage in clouds and could be a new oxidation pathway for H₂S in terrestrial, geothermal and volcanic regions.