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 <b>S</b>_<b>8</b> ring upon photoexcitation employing advanced nonadiabatic dynamics simulations. Our findings reveal that the bond breaking of the <b>S</b>_<b>8</b> ring occurs within tens of femtoseconds. At the time of bond breaking, most molecules are in the lowest singlet excited state S₁. S₁ survives for 40-450 fs before relaxing to the quasi-degenerate manifolds formed by the T₁ and S₀ states of the <b>S</b>_<b>8</b> chain. This suggests that upon photoexcitation the polymerization of the <b>S</b>_<b>8</b> chains might proceed before the chains relax to their lowest energy states. The derived temporal resolution provides a detailed perspective on the dynamics of <b>S</b>_<b>8</b> rings upon photoexcitation, shedding light on the intricate processes involved in its excited-state transformations.