Well-resolved fluorescence spectra are reported for single crystals of
C-60 at 1.2 K. The fluorescence is found to be composed of two contri
butions. Fluorescence-microwave double-resonance experiments indicate
that the dominant component originates from deep X-traps that consist
of pairs of C-60 molecules. The minor component most likely derives fr
om shallow monomolecular C-60 X-traps.