Photo-induced Metastable State of S8Clusters in Liquid Sulfur

Abstract

AbstractIt is well known that liquid sulfur undergoes a polymerization transition from S8 rings to the mixture of S8 rings and polymeric chains at Tp=159°C. In addition to the transition, it has been known that there is a transformation from S8ring to a molecular species other than S8ring and polymeric chain below Tpsince 19thcentury. Such molecular species can also be obtained by the illumination of light. Several models of the molecular form have been presented. However, the conclusive model which explains all experimental results has not been settled yet. Recently we measured transient photo-induced optical absorption in liquid sulfur and Munejiri et al. performed first-principles molecular-dynamics simulations to clarify the microscopic origin of the experimental results. The results of the simulations presented a plausible molecular form as the molecular species, which is a tadpole-shaped S8 cluster. We show that the molecular form clearly explains the previous experimental results. A possibility of the formation of an intimate valence alternation pair in the small cluster is also discussed.