Knowledge Bank

Excitation of both the $24E\prime \leftarrow 14A2\prime$ transition of $Na3$ and the $14A2\prime \prime \leftarrow 14A2\prime$ transition of $K3$ 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 $K3$ than for $Na3$ while, for the latter system, the rapidity of the process increases as we move to higher vibronically excited states.