A computational study of radiationless deactivation mechanisms of furan

Abstract

Possible mechanisms for the radiationless deactivation of photo-excited furan have been investigated using high-level electronic structure methods. Two different conical intersections between the S 0 and S 1 electronic states have been characterized, both involving various degrees of CO bond cleavage. One of these corresponds to a planar ring-opened structure and the other to an asymmetric ring-puckered structure. Calculations have been performed in order to establish the vertical electronic spectrum and to investigate the behaviour of the potential energy surfaces as the intersections are approached. The present results indicate that both crossings can be accessed through exothermic and barrierless processes after vertical excitation into the optically bright S 2( ππ∗) state. These features make them good candidates to account for efficient radiationless deactivation in furan. The deactivation pathways considered in the present work are close analogues of those previously described for other five-membered heterocycles.