Raman studies of alkali-metal doped A(x)C60 films (A = Na, K, Rb, and Cs; x = 0, 3, and 6)

The room temperature Raman spectra of the intramolecular modes between 100/cm and 2000/cm are reported for alkali-metal doped A(x)C60 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 A(g) symmetry and only the lowest frequency H(g) mode. The other H(g) 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 change transfer in these films.