Light-Induced Ring-to-Chain Transformations of Elemental Sulfur: Nonadiabatic Dynamics Simulations.

The emergence of high-sulfur content polymeric materials and their diverse applications underscore the need for a comprehensive understanding of the ring-to-chain transformation of elemental sulfur. In this study, we delve into the ultrafast transformation of the elemental sulfur ring upon photoexcitation employing advanced nonadiabatic dynamics simulations. Our findings reveal that the bond breaking of the ring occurs within tens of femtoseconds. At the time of bond breaking, most molecules are in the lowest singlet excited state S. S survives for 40-450 fs before relaxing to the quasi-degenerate manifolds formed by the T and S states of the chain. This suggests that upon photoexcitation the polymerization of the chains might proceed before the chains relax to their lowest energy states. The derived temporal resolution provides a detailed perspective on the dynamics of rings upon photoexcitation, shedding light on the intricate processes involved in its excited-state transformations.