The dependence of the symmetry (spin) forbidden photoluminescence of C60 molecules on their proximity to metal

We find out that a monolayer of C60 molecules in close proximity (0–4 nm) to an Au substrate exhibits a striking photoluminescence in both the visible and near-IR due to the radiative recombination of singlet and triplet excitions, respectively. The luminescence is observed even when the C60 molecules are in direct contact with the metal. This is the first observation of a molecular triplet luminescence that is induced by a metal substrate, which is all the more remarkable since a metal substrate normally quenches the luminescence of adsorbed molecules.