High-field electron spin resonance experiments have been performed on
an Er fullerene extract, containing about 1% endohedral Er fullerenes
(Er-m@C-82) The ESR spectra of (Er-m@C-82) show two resonances, which
we propose to originate from the (Er-m@C-82) molecules, one resonance
from an unpaired electron on the fullerene cage and one from the Er34f electrons.