Equilibrium phases in alkali metal doped C/sub 60/ films and single crystals from IN-SITU infrared reflectivity measurements

Summary form only given. In situ IR-reflectivity measurements are reported for K and Rb doped C/sub 60/ films and single crystals. In the spectral range of the four F/sub 1u/ modes we analysed the change of these modes as a function of doping. By iterative doping and annealing processes we obtained nearly pure phases of A/sub x/C/sub 60/ (x = 0, 1, 3, 4, 6). A quantitative analysis of the reflectivity spectra using a multilayer response function revealed the line positions, linewidth and the oscillatorstrength for the F/sub 1u/ modes. The second lowest mode and the highest mode showed good agreement with the charged phonon model with respect to line shift and absorption intensity.