Excimer-laser-induced permanent electrical conductivity in solid C60 films

After being irradiated in air by a XeCl (308 nm) excimer laser, the electrical conductivity of solid thin-film C60 has been improved by more than six orders of magnitudes. The products resulting from laser irradiation of C60 films have been investigated by Raman scattering and the onset of conductivity can be attributed to laser-induced oxygenation and disintegration of the fullerene. Irradiated by ∼40 ns laser pulses with different fluence, products with different microstructure were observed. At lower fluence, the Raman features of microcrystalline graphite and fullerene polymer were observed. At a fluence just below the ablation threshold (36 mJ/cm2), the fullerene molecules in the film were disintegrated completely and transformed to amorphous graphite. (orig.). With 5 figs