First-principles dynamics of collisional intersystem crossing: resonance enhanced quenching of C(1D) by N2

Abstract

Intersystem crossing is a common and important nonadiabatic process in molecular systems, and its first-principles characterization requires accurate descriptions of both the electronic structure and nuclear dynamics. Here, we report an accurate full-dimensional quantum dynamical investigation of collisional quenching of the excited state C(¹D) atom to its ground state C(³P) counterpart by N₂, which is an important process in both combustion and interstellar media, using full-dimensional ab initio potential energy surfaces and spin–orbit couplings. Satisfactory agreement with experimental rate coefficients is obtained. Despite relatively small spin–orbit couplings, it is shown that intersystem crossing is efficient because of multiple passages via long-lived collisional resonances.