C₆₀ Photo-Polymerization using Free Electron Laser

抄録

  This paper is the review for the authors' works on Free Electron Laser (FEL) irradiation effects aiming at syntheses of 3-dimensional C₆₀ polymers. The used pristine was 99.5% C₆₀ powder or the mixture with iodine, and also C₆₀ precipitates prepared by a liquid-liquid interfacial precipitation (LLIP) method. The pristine was set in the vacuum and was compressed in the anvil with the pressure of 600 MPa～7 GPa. The third harmonics (@400-500 nm) FEL was irradiated with a macro-pulse (@20 μs) containing very short micro-pulses (@200 fs). The Raman Ag(2) peak of C₆₀ molecules in the vicinity of 1469 cm^-1 becomes broad and shifts to the lower energy side as proceeding of polymerization. Under higher pressure the larger red-shift and the increment of the half width of the Raman peak were observed. The irradiated mixture with iodine revealed the more distinctive red-shift, above 10 cm^-1. Also the large peak red-shift ca. 10cm^-1 was observed in the LLIP specimen probably because of highly packing of C₆₀ molecules. The obtained results suggested that the C₆₀ molecular accession and/or the photon-assisted hole-doping from iodine were decisively effective to promote photo-polymerization.