The energy redistribution processes in C60 trapped in low temp. rare gas solids have been studied using one- and two-color femtosecond pump-probe spectroscopy. The data show an ultrafast internal conversion process, followed by a slower electronic relaxation among the lowest singlet states. That data are compared to results obtained in pure solid films of C60. They suggest that the intramol. relaxation is also dominant in these later cases. [on SciFinder (R)]