The harmonics of a free electron laser (FEL) were irradiated in vacuum to surfaces of compressed C-60 and a mixture Of C-60 and I-2. The power and frequency of the fundamental FEL macro-pulse were ca. 0.5 mJ/pulse and 2 Hz, respectively. The irradiation time was 120-180 min. After irradiation of FEL with a typical wavelength of 450 or 345 nm, the Raman peak of Ag(2)-derived vibration mode Of C60 shifted to the lower-energy side. The Raman peak shift of the mixture powder sample was greater than that of pure C-60. Furthermore, changes of the crystalline structure indicated that various intermolecular combinations occurred by irradiation. These results strongly suggest that three-dimensional polymerization Of C-60 was promoted by laser irradiation and the effect of photon-assisted hole-doping from iodine atoms to C-60 molecules. (c) 2007 Elsevier B.V. All rights reserved.