Simultaneous Observation of Triplet and Singlet Cyclopentane-1,3-diyl Diradicals in the Intersystem Crossing Process

摘要

Intersystem crossing is an important chemical process. In this study, the rate constant of intersystem crossing, k(ISC) similar to 3 x 10(7) s(-1), for cyclopentane-1,3-diyl diradicals was unequivocally determined by the simultaneous observation of the decay process of the triplet diradical (lambda(obs) = 320 nm) and the growth process of the corresponding singlet diradical (lambda(obs) = 560 nm). The two spin states were directly observed using a long-lived singlet 2,2-dimethoxy-1,3-diphenylcyclopentane-1,3-diyl diradical.