Direct optical excitation of a fullerene-incarcerated metal ion

The endohedral fullerene Er3N@C80 shows characteristic 1.5 μm photoluminescence at cryogenic temperatures associated with radiative relaxation from the crystal-field split Er3+4I13/2 manifold to the 4I15/2 manifold. We present direct non-cage-mediated optical interaction with the erbium ion, and have used this to complete a photoluminescence-excitation map of the Er3+4I13/2 manifold.