Empty fullerenes are known to have very fast intersystem crossing with near 100% yield of the T₁ state, which results in very low quantum yield of fluorescence and relatively short fluorescence lifetimes (less than 1 ns). In endohedral metallofullerenes, the intersystem crossing is even faster due to the internal heavy-atom effect, and hence fluorescence can hardly be expected. However, Y₃N@C₈₀ is known to exhibit reasonably high yield of fluorescence (1%) and unusually long lifetimes of 800 ns.^{1, 2} Such unusual photophysical parameters indicate that simple fluorescence mechanism cannot explain experimental facts. In this contribution we describe steady-state and lifetime luminescence as well as light-induced electron paramagnetic resonance studies of Y₃N@C₈₀ at different temperatures aimed at clarification of photophysical properties of Y₃N@C₈₀.

1. Bharadwaj, L.; Novotny, L., Plasmon-Enhanced Photoemission from a Single Y₃N@C₈₀ Fullerene. J. Phys. Chem. C 2010, 114, 7444-7447.

2. Toth, K.; Molloy, J. K.; Matta, M.; Heinrich, B.; Guillon, D.; Bergamini, G.; Zerbetto, F.; Donnio, B.; Ceroni, P.; Felder-Flesch, D., A Strongly Emitting Liquid-Crystalline Derivative of Y₃N@C₈₀: Bright and Long-Lived Near-IR Luminescence from a Charge Transfer State. Angew. Chem.-Int. Edit. Engl. 2013, 52, 12303-12307.