OPTICAL-EMISSION SPECTROSCOPY OF LASER-PRODUCED CARBON PLASMA AT MODERATE AND LOW IRRADIANCE IN AN AMBIENT ATMOSPHERE

The plasma produced during pulsed-laser deposition of thin carbon film s is studied in the presence of ambient gases (Air, He, Ar) at low and moderate irradiances of Nd:YAG laser. The presence of ambient gas sho ws a pronounced effect on the dynamics of the plasma plume. At moderat e intensity, we report an appearance of a peculiar double-peak structu re in the temporal profile of the C II transition in laser-produced ca rbon plasma as it expands into a background gas. We believe that the s tructure originates mainly due to stratification of the plasma into fa st and slow ion components at the interface where Rayleigh-Taylor inst ability occurs. Thin carbon films deposited on silicon in the presence of argon gas have shown the characteristic features of diamond-like c arbon in X-ray diffraction and Raman Spectroscopy. The X-ray diffracti on pattern of carbon film deposited at 1 torr of argon gas pressure sh ows the dominance of (111), (220), (311), and (400) crystalline plane of cubic diamond.