Spectroscopic Characterization of S<sub>3</sub>O Isomers: Potential Contributor to the Unknown UV Absorber in Venus’s Atmosphere
Tarek Trabelsi
Abstract
A long-standing question about Venus’s atmosphere concerns the origin and distribution of the mysterious ultraviolet (UV) absorber, which is responsible for the absorption band observed in the near-UV and blue regions of Venus’s spectrum. In this work, we investigate the electronic structure of S 3 O isomers, their excited states, and their photoabsorption cross sections using quantum chemistry methods. Our results demonstrate that the cis- and trans-S 3 O isomers exhibit strong absorption in the 300–500 nm range, making them plausible candidates for the unknown near-UV absorber. The electronic spectrum of ring-S 3 O is featureless, whereas planar-S 3 O exhibits absorption around 300 nm. Additionally, spectroscopic data were generated using vibrational configuration interaction (VCI) for the most stable isomer and its isotopes to aid in their detection in the laboratory or the interstellar medium. This study provides valuable insights into the photochemistry of S 3 O isomers and the complex sulfur chemistry within Venus’s atmosphere.