Improving the Signal-to-Noise Ratio of Atomic Transition Peaks in LIBS Using Two-dimensional Correlation Analysis

Abstract

In this stu dy, two dimensional ( 2D correlation analysis wa s utilized for achieving a significant improvement in the signal to noise (S/N) ratio of laser induced breakdown spectroscopy (LIBS) data . Time resolved LIBS spectra of metallic, bimetal lic targets and the normal LIBS spectra of bimetallic targets with varying compositions were used for the detailed analysis . The diagonal of the matrix in the synchronous spectra was used to demonstrate the improvement in the S/N ratio. An improvemen t in the peak intensities by few order s of magnitude accompanied by suppression in the noise was observed. The correlations between LIBS peaks were also visualized using 2 D plots. Correlation strengths of atomic transitions were visualized in Aluminum (Al), Copper (Cu), and Brass whereas correlation strengths of atomic, atomic, and ionic transitions were visualized in Au Ag bimetallic targets with different compositions (Au30Ag70, Au50Ag50, Au80 Ag20). The improved spectra were subsequently used in the principal component analysis for classification studies of four compositions of bimetallic targets Au20Ag80, Au30Ag70, Au50 Ag50, and Au80Ag20 The variance of the first three principal components were found to be improved from the analysis. The accumulated percentage of explained variance of 95 was achieved with the first three components from improved spectra whereas only ~ 80 was achieved with the regular LIBS spectra from PCA studies