Observation and identification of the molecular triplet in C60 thin films

The excited state properties of C60 thin films have been probed at 77 K using Raman spectroscopy. The change in the Raman, A2g mode of C60, whose position is largely independent of temperature was monitored as a function of the excitation intensity at 514.5 nm. This mode, normally positioned at 1469 cm−1, was seen to shift to a lower Raman frequency with increasing laser intensity. Two excited state species have been identified. The first, at 1466 cm−1, has been associated with the molecular triplet of C60, while the second species, at 1463 cm−1, has been speculated to be an excited state co-operative in the solid.