Photochemistry of CF3Cl: Quenching of Charged Fragments Is Caused by Nonadiabatic Effects

WOS:000444792700029International audienceFor the first time, high-level multireference electronic structure calculations have been performed to study the photochemistry of CF3Cl, allowing a comprehensive interpretation and assignment of experimental data concerning fluorescence, ion-pair formation, and generation of CF3 fragments in several electronic states. All studied dissociation channels correlate either with Cl or Cl in the ground state. On the other hand, CF3 fragment can be generated either in the ground or excited state. A rationalization for the nonadiabatic relaxation of CF3Cl, including the formation of an (n4s) stable state and internal conversion at multiple-state intersections, has been provided. Our results explain the anomalous quenching of charged fragment after low-energy excitation experimentally observed by separate groups. We show that the CF3 +… Cl ion pair undergoes an internal conversion to the ground state, producing neutral CF3 and Cl fragments. The results also allow understanding why CF3Cl is usually a non-emitting species and how UV emission could be induced. de Medeiros et al., Photochemistry of CF3Cl (2018)