Temperature dependence of Raman scattering in K₃Ba₃C₆₀

Raman spectra at different temperatures are reported for K₃Ba₃C₆₀. A systematic change of the Raman spectra with temperature is observed. The development of the linewidth and intensity for all modes with decreasing temperature is in sharp contrast to the case for pure C₆₀. For the two lowest-frequency H_g modes, the appearance of the low-frequency components and an increase in their intensity are observed as temperature decreases. This could be related to an internal strain between the doped part of the crystal and the undoped part of the crystal, and the Jahn-Teller effect. An anomalously large upshift of 9 cm_-1 between 20 K and room temperature for the pinch A_g (2) mode suggests the existence of hybridization between the CM molecules and the intercalants. The doublet of A_g(l) at low temperature could arise from the splitting of the crystal field.