Basic investigations for laser microanalysis: III. Application of different buffer gases for laser-produced sample plumes

We have measured the diameters and depths of craters in a copper sample and the amount of material ablated by the 1.06-m radiation of a pulsed Nd: YAG laser in the buffer gases argon, neon, helium, air and nitrogen as well as the emission intensities of analyte atoms in dependence on laser power and buffer gas pressure. The results are correlated with corresponding data of the plasma temperatures and the relative electron densities in the plasma. Criteria for the choice of the buffer gas, the buffer gas pressure and the laser power for optical emission spectrometry of microplasmas are given.