Development of r.f. powered helium glow-discharge optical emission spectrometry associated with sampling by laser ablation

In order to improve the precision of depth profiling in glow-discharge optical emission spectrometry, sampling from the sample electrode with laser ablation and excitation of the sample atoms with an r.f. helium glow plasma have been attempted for a glow- discharge emission source. Consequently, it has been found that sample atoms can be introduced into the glow plasma by laser ablation, and excitation of the atoms with the r.f. helium glow plasma is possible during a period of between 100 μs and 7 ms after the irradiation of a Q-switched Nd : YAG laser. Since the r.f. helium glow plasma has little sputtering ability, the sampling and the excitation processes can be controlled independently; thus, the above-mentioned procedure would improve the precision of depth profiling in glow-discharge optical emission spectrometry. In addition, an enhancement of the emission intensity and the production of metastable helium atoms were observed by using a bias-current conducting method described in our previous paper. These effects could also improve the sensitivity in glow-discharge optical emission spectrometry.