TEMPORAL AND SPATIAL EVOLUTION OF CA IN LASER-INDUCED PLASMA FROM GRAPHITE TARGET

Laser ablation of graphite has been carried out using 1.06 mu m radiat ion from a Q-switched Nd:YAG laser and the time of flight distribution of molecular C-2 present in the resultant plasma is investigated in t erms of distance from the target as well as laser fluences employing t ime resolved spectroscopic technique. At low laser fluences the intens ities of the emission lines from C-2 exhibit only single peak structur e while beyond a threshold laser fluence, emission from C-2 shows a tw in peak distribution in time. The occurrence of the faster velocity co mponent at higher laser fluences is explained as due to species genera ted from recombination processes while the delayed peak is attributed to dissociation of higher carbon clusters resulting in the generation of C-2 molecule. Analysis of measured data provides a fairly complete picture of the evolution and dynamics of C-2 species in the laser indu ced plasma from graphite. (C) 1996 American Institute of Physics.