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

• Published in: Journal of chemical theory and computation 2018-09, Vol.14 (9), p.4844-4855
• Main Authors: de Medeiros, Vanessa C, de Andrade, Railton B, P. Rodrigues, Gessenildo, Bauerfeldt, Glauco F, Ventura, Elizete, Barbatti, Mario, do Monte, Silmar A
• Format: Article
• Language: English
• Subjects: Chemical Sciences; or physical chemistry; Theoretical and
• ISSN: 1549-9618; 1549-9626
• DOI: 10.1021/acs.jctc.8b00457

For 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, a 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 a charged fragment after low-energy excitation, a fact 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 as to why CF3Cl is usually a nonemitting species and how UV emission could be induced.