Raman Studies of Alkali-Metal Doped AxC60 Films (A = Na, K, Rb, and Cs; x = 0, 3, and 6)

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Science  13 Dec 1991:
Vol. 254, Issue 5038, pp. 1625-1627
DOI: 10.1126/science.254.5038.1625


The room temperature Raman spectra of the intramolecular modes between 100 cm–1 and 2000 cm–1 are reported for alkali-metal doped AxC60 films. For A = K, Rb, and Cs, phase separation is observed with the spectra of C60, K3C60, K6C60, Rb3C60, Rb6C60, and Cs6C60 phases reported. The x = 3 phases show only three Raman active modes: two of Ag symmetry and only the lowest frequency Hg mode. The other Hg modes regain intensity in the x = 6 films, with several mode splittings observed. For A = Na, such phase separation is not clearly observed, and reduced mode shifts are interpreted as due to incomplete charge transfer in these films.