15min:

GIACINTO SCOLES, JAMES REHO, JOHN P. HIGGINS, CARLO CALLEGARI AND KEVIN K. LEHMANN, Department of Chemistry, Princeton University, Princeton, NJ 08544.

Excitation of both the 2⁴E'<-1⁴A'₂ transition of Na₃ and the 1⁴A''₂<- 1⁴A'₂ transition of K₃ lead to curve-crossings into a predissociative doublet state as evidenced by the presence of atomic (P-> S) and singlet dimer B-> X fluorescing products. Single photon counting techniques have been employed to measure the intersystem crossing times in these simple systems by measuring the onset times of product fluorescence as a function of the vibrational state of the upper quartet state. We find that the spin-orbit mediated intersystem crossing occurs as expected more rapidly for K₃ than for Na₃ while, for the latter system, the rapidity of the process increases as we move to higher vibronically excited states.