Determination of elemental depth profiles by multi-spot averaging technique of LIBS spectra

The paper deals with the development of the laser induced breakdown spectroscopy (LIBS) into an in situ method for studying of erosion/deposition processes at the first walls of fusion reactors. Because of fluctuations in the signal-to-background ratio of single-shot LIBS spectra, an averaging procedure has been used to reliably determine depth profiles of different elements at the surface, including that of deuterium. In the present study the averaging was carried out over LIBS spectra recorded from different sites of the studied sample. The set up allowed the characterization of nth laser shot by spectra recorded from N different sites. Deuterium-doped and Al-coated Ti samples were tested. The required ablation was produced by a UV (λ = 248 nm) laser. LIBS results for the depth profiles of D, Al, and Ti were compared with the data obtained by three different ion-beam techniques. Comparison of the averaged intensity of elemental spectral lines of an element versus laser shot number curves with depth profiles obtained by other methods showed a good qualitative match.