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

We have studied the transformations of amorphous hydrogenated carbon films (a-C: H) induced by pulsed laser irradiations. By the complementary use of isotopic (hydrogen/deuterium) tracing experiments and nuclear microanalysis, the changes induced by the laser treatments in the elemental 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 large exchange phenomenon was evidenced between the deuterium atoms initially incorporated in the amorphous carbon layers, and hydrogen atoms coming from the ambient water vapour. These findings are certainly related to the thermal effects induced in the a-C:H films by the laser pulses.