Polyimide polymers can be converted from an insulator to a conductor by suitably pulsed excimer laser irradiation. The ultraviolet light is strongly absorbed by the polymer and pyrolyzes the material into carbon clusters. The formation of those clusters is accompanied by an increase of both electric and thermal conductivity. We observed photothermally the steep rise of thermal diffusivity when the density of the electrically conducting clusters exceeded the percolation threshold. This finding illustrates the charge carriers contribution to the kinetic energy transport in disordered materials.
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1999
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