Physical properties and phase transitions in AC60 Original Research Article

The phase transitions from an fcc to an orthorhombic structure were studied in detail for the AC60 compounds. For moderately fast cooling (10 K min−1, continuously) RbC60 and KC60 gave an overall identical spectra. In the frequency range of the former Ag(2) pinch mode two components were detected. There origin could be explained assuming a Davidov splitting or by modes which become Raman active in the orthorhombic structure. Quenching and annealing experiments carried out with the RbC60 fcc high temperature phase showed significant changes in the spectrum which were interpreted as the Raman response of a metastable monomer and a single-bonded dimer phase.