Raman, x-ray diffraction, and photoemission measurements on C60 and doped C60 films

We present results from a study of the vibrational, structural, and electronic proper-ties of three samples, C-60 powder, thin films of C-60 and La-doped C-60 We present Raman data for C-60 powder subjected to pressures in a diamond anvil cell, ranging from 0,5 to 14,7 GPa, The material undergoes a structural phase transition between 9,1 and 14,7 GPa. Some of the frequencies of the Raman-active modes soften, while others harden with increasing pressure, The x-ray diffraction data show fcc crystalline structure in the powder and La-doped C-60 films. The C-60 film, however, appears disordered. The electronic valence bands of thin films were measured by photoemission spectroscopy. We observe a higher density of the electronic states in the doped sample.