The proposed reactions for efficient sulfur particles formation may help to understand the long sought-after identity of the enigmatic ultraviolet absorber on the atmosphere of Venus.

The atmosphere of Venus has abundant SO2 and sulfuric acid particles. The ultraviolet destruction of SO2 is expected to produce sulfur particles, built up from atomic S to S2, then S4 and finally S8. Here we explore how this process is initiated, how S2 is formed. One possibility is to form S2 from two sulfur atoms, that is, reaction of S and S. Molecules of S2 and S2 can then combine to form S4, and so on. Sulfur particles can form either by condensation of S8 or by condensation of S2, S4 and other allotropes which then rearrange to form condensed S8. This paper explores the initial S2 formation by an alternative pathway by using computational chemistry. The results suggest a new pathway for S2 formation, the SO and S2O, which is much faster than combining two S atoms to make S2, thereby providing a faster route to sulfur particle formation and perhaps playing a role in the formation of the enigmatic UV absorber. Antonio Francés-Monerris, Javier Carmona-García, Tarek Trabelsi, Alfonso Saiz-Lopez, James R. Lyons, Joseph S. Francisco, and Daniel Roca-Sanjuán. Photochemical and thermochemical pathways to S2 and polysulfur formation in the atmosphere of Venus. Nature Communications, DOI: 10.1038/s41467-022-32170-x