  We present an electron paramagnetic resonance (EPR) study of ErSc2N@C80
fullerene in which there are two Er3+ sites corresponding to two different
configurations of the ErSc2N cluster inside the C80 cage. For each
configuration, the EPR spectrum is characterized by a strong anisotropy of the
g factors (gx,y = 2.9, gz = 13.0 and gx,y = 5.3, gz = 10.9). Illumination
within the cage absorption range (<600 nm) induces a rearrangement of the
ErSc2N cluster inside the cage. We follow the temporal dependence of this
rearrangement phenomenologically under various conditions.
