Expansion dynamics of laser ablated carbon plasma plume in helium ambient

Time resolved emission spectroscopic measurements on a plasma plume generated by pulsed laser ablation of carbon in helium ambient atmosphere have been performed. Temporal pro®les of electronically excited C2 species show a twin peak distribution beyond a threshold laser irradiance. The emission features of C2 species are found to be signi®cantly in¯uenced by the ambient helium atmosphere. It is observed that the helium ambient pressure and laser irradiance have opposite effects on the expansion dynamics of C2 species. # 2001 Elsevier Science B.V. All rights reserved.