Improvements in depth-profiling of thick samples by laser-induced breakdown spectroscopy using linear correlation

In this work, the capability of linear correlation for depth profiling by laser-induced breakdown spectroscopy (LIBS) is studied for the first time. A software was specially developed for the calculus of the linear correlation coefficients and its representation in the format of depth profiles. Thick layered samples (layers with thickness of tens to hundreds of micrometers) of different nature, archaeological ceramics and polymer coatings on steel, were characterized by LIBS using the conventional approach based on intensity profiles, and the correlation method. The results revealed that, without using any normalization, the comparison of LIB spectra through the linear correlation coefficient gave an improvement of the depth profile quality and the interface localization by minimizing the influence of fluctuations and decay of the signals in the global intensity of spectra, caused by sources other than concentration variations. Copyright (C) 2006 John Wiley & Sons, Ltd.