Gas dynamic effects on formation of carbon dimers in laser-produced plasmas

We investigated the effect of helium and nitrogen pressures on the dynamics of molecular species formation during laser ablation of carbon. For producing plasmas, planar carbon targets were irradiated with 1064 nm, 6 ns pulses from an Nd:yttrium aluminum garnet laser. The emission from excited C(2) and CN molecules was studied using space resolved optical time-of-flight emission spectroscopy and spectrally resolved fast imaging. The intensity oscillations in C(2) and CN monochromatic fast imaging and their emission space-time contours suggest that recombination is the major mechanism of C(2) formation within the laser ablation carbon plumes in the presence of ambient gas. (C) 2011 American Institute of Physics. [doi:10.1063/1.3645631]