Disentangling Electronic and Vibrational Effects in the Prediction of Band Shapes for Singlet-Triplet Transitions

The band shape of phosphorescent emission of benzophenone has been computed by using the first order perturbative expansion of singlet and triplet states with the spin-orbit coupling operator as perturbation and by evaluating Franck-Condon integrals with an efficient strategy for handling the whole set of vibrational coordinates. The computed band shape compares well with the experimental one, showing that modern computational tools yield reliable spin-orbit couplings to be used for evaluating the rates of singlet-triplet transitions in modern optoelectronic devices.