The vibrational Raman spectra of purified solid films of C60 and C70

A technique to produce samples consisting primarily of C60 and C70 by fractional sublimation of carbon soot was found and used to produce solid films of these molecules. Film compositions were determined using a surface analytical mass spectrometric technique. Vibrational Raman spectra of the purified films were measured and vibrational lines of both C60 and C70 are identified. A C60 line at 273 cm−1 is observed, in agreement with theoretical predictions for the lowest frequency Hg “squashing” mode of Buckminsterfullerene. The two strongest C60 lines, found at 1469 and 497 cm−1, can consistently be assigned to the two totally symmetric Ag modes on the basis of their frequencies and measured depolarization ratios.