Time-resolved emission studies of ArF-laser-produced microplasmas

ArF-laser-produced microplasmas in CO, CO2, methanol, and chloroform are studied by time-resolved emission measurements of the plasma decay. Electron densities are deduced from Stark broadening of the line profiles of atomic H, C, O, and Cl. Plasma ionization and excitation temperatures are determined from measurements of relative populations of ionic and neutral species produced in the plasmas. A discussion of the thermodynamic equilibrium status of ArF-laser microplasmas is presented. In general, the ArF-laser-produced microplasma environment is found to be similar in all the gases studied, in terms of both temperature (15,000–20,000 K) and electron density (1017 cm−3–1018 cm−3), despite the considerable differences observed in the breakdown thresholds and relative energies deposited in the various gases.