NON-ADIABATIC PROCESSES IN THE PHOTODISSOCIATION OF QUARTET STATE $Na_{3}$ and $K_{3}$

Abstract

Excitation of both the $2^{4}E^{\prime}\leftarrow 1^{4}A_{2}^{\prime}$ transition of $Na_{3}$ and the $1^{4}A_{2}^{\prime\prime}\leftarrow 1^{4}A^{\prime}_{2}$ transition of $K_{3}$ lead to curve-crossings into a predissociative doublet state as evidenced by the presence of atomic $(P \to S)$ and singlet dimer $B \to X$ 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 $K_{3}$ than for $Na_{3}$ while, for the latter system, the rapidity of the process increases as we move to higher vibronically excited states.