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

Vanessa C de Medeiros (1) , Railton B de Andrade (1) , Gessenildo P. Rodrigues (1) , Glauco F Bauerfeldt (2) , Elizete Ventura (1) , Mario Barbatti (3) , Silmar A Do Monte (1)

1 UFPB - Universidade Federal da Paraiba / Federal University of Paraiba
2 Instituto de Ciências Exatas - ICE
3 ICR - Institut de Chimie Radicalaire

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, 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) 2

Mots clés: Photochemistry; CF3CI

Domaines: Chimie; Chimie théorique et/ou physique

Vanessa C de Medeiros, Railton B de Andrade, Gessenildo P. Rodrigues, Glauco F Bauerfeldt, Elizete Ventura, et al.. Photochemistry of CF3Cl: Quenching of Charged Fragments Is Caused by Nonadiabatic Effects. Journal of Chemical Theory and Computation, 2018, 14 (9), pp.4844-4855. ⟨10.1021/acs.jctc.8b00457⟩. ⟨hal-01965454⟩