Nitrogen laser ablation analysis using the primary plasma as a standard for the quantification of vaporised atoms
The characteristics of the primary plasma, which is produced just above the surface of a target when it is irradiated with focused nitrogen (N2) laser light, is studied using time-resolved spectrometry. It is found that the primary plasma emits a fairly continuous emission spectrum in the visible region for about 10 ns, and that the spectrum distribution is virtually independent of the type of target used.
On the assumption that the intensity of the primary plasma is proportional to the number of atoms vaporised from the target, the intensity of the analytical emission line can be normalised. By using this standardisation method, quantitative determinations are carried out for Si, Ni, Cu, Zn, Sn and W in various metals, resulting in a fairly good linear relationship between the normalised emission line intensity and the content.