Cage exit supported by spin–orbit coupling: quantum model simulations for ClF in an Ar matrix

Quantum simulations of the wavepacket dynamics of a two-dimensional model representing ClF in Ar driven by an ultrashort laser pulse demonstrate that intersystem crossing (ISC) may serve as decisive step to cage exit. Specifically, the laser pulse induces a Franck–Condon type transition to the 1Π state. Subsequently, the ClF bond is stretched quasi-periodically, and its center of mass is shifted to a position where the 1Π state is near degenerate with the neighbouring 3Π state. Here, spin–orbit coupling induces efficient ISC from the 1Π to the 3Π state, and a favourable shelf-type topology of the potential energy surface (PES) of the 3Π state allows penetration of the wavepacket into the neighbouring cage.