LASER-INDUCED MODIFICATIONS IN A-C-H THIN-FILMS

We have studied the transformations of amorphous hydrogenated carbon f ilms (a-C: H) induced by pulsed laser irradiations. By the complementa ry use of isotopic (hydrogen/deuterium) tracing experiments and nuclea r microanalysis, the changes induced by the laser treatments in the el emental composition of the films were evidenced. The loss of deuterium atoms was accompanied by a graphitization of the films. In addition, even at laser intensities much lower than the ablation threshold, a la rge exchange phenomenon was evidenced between the deuterium atoms init ially incorporated in the amorphous carbon layers, and hydrogen atoms coming from the ambient water vapour. These findings are certainly rel ated to the thermal effects induced in the a-C:H films by the laser pu lses.