Structural stability of C60 films under the irradiation by swift heavy ions

The irradiation experiments of thin C60 film stacks were performed by S, Fe, Xe, and U ions with energy of GeV delivered by HIRFL at Lanzhou in China,and Unilac in Germany respectively, and 120keV H ions delivered by ion Implantor at Institute of Modem Physics, Chinese Academy of Sciences. The structural stability of C60 films under the irradiation by swift heavy ions or high density electronic excitation effects were analyzed by means of FTIR, XRD, XPS and Raman scattering spectroscopies. The analysis results indicated that the irradiations induced the polymerization and destruction of C60 molecules, some components of high-temperature-high-pressure phase of the polymerized C60 appeared in the irradiated C60 films and finally amorphous transformation of C60 films took place. The electronic energy transfer dominates the damage process of C60 films. The partial recovery of the damage in irradiated C60 films at certain electronic energy loss is attributed to an annealing effect of high density electronic excitation. (authors)