Spectroscopic characterization of laser-produced GaAs plasma in helium and argon background gases

Optical emission from laser produced plasma of GaAs was studied for various helium and argon background pressures. The pressure was changed in the range from 5×10−3 to 100 mbar. The time evolutions of selected atomic and ionic spectral transitions were measured and compared. Several different maxima in the temporal evolution of As and Ga optical emission were observed and explained by the processes in plasma. These processes also explain some of the pressure dependencies of the integrated emission intensities. It was found that while argon background gas was more efficient in exciting plasma species, helium led to more uniform species’ ratios over larger pressure range.