Formation mechanisms of carbon dimer in excimer laser produced plasma

Fundamental physical processes involved in carbon excimer laser produced plasma were investigated through high resolution spectroscopic measurements. The spectral emitting features near the target (within 1 mm from it) of different plasma components were recorded at various instants from the laser pulse, with a special emphasis on the carbon dimer known to have a major influence in the synthesis of high-quality carbon-based materials. The dominance of the recombination processes in the dimer formation is deduced from: (i) the existence of multiple time-decay constants evidenced for the spectral lines belonging to various plasma species. These parameters are attributed to the formation of the respective species through different and complex mechanisms, and they are discussed from the perspective of possible deviations from the local thermodynamic equilibrium; (ii) the longer emission time of the carbon dimer compared with singly charged ion or of the neutral. (iii) the increase in time of the vibrational temperature that associated to the carbon molecule.