Characterization of carbon films produced by laser ablation of graphite in helium and nitrogen gas atmosphere

Laser ablation of graphite was carried out in vacuum and in a nitrogen or helium gas atmosphere and the structure of the deposited films were analyzed. Nitrogen gas was supplied with or without microwave discharge to vary the reactivity. The film produced in helium was found by Raman spectroscopy to be more graphitic than the vacuum-deposited film and to contain acetylenic carbon chain. A similar trend was observed for the film obtained in nitrogen without discharge, with a trace amount of nitrogen inclusion found by XPS. In contrast, by using microwave discharge, the nitrogen content increased by a factor of about seven and the existence of nitrogen-containing aromatic structure together with cyanic group was indicated by FTIR spectroscopy.