Time resolved analysis of C-2 emission from laser induced graphite plasma in helium atmosphere

We report time resolved study of C-2 emission from laser produced carbon plasma in presence of ambient helium gas. The 1.06 mu m radiation from a Nd:YAG laser was focused onto a graphite target where it produced a transient plasma. We observed double peak structure in the time profile of C-2 species. The twin peaks were observed only after a threshold laser fluence. It is proposed that the faster a velocity component in the temporal profiles originates mainly due to recombination processes. The laser fluence and ambient gas dependence of the double peak intensity distribution is also reported.