The emission intensity enhancement and improved limit of detection of Cu, Ag, and Au using electric field assisted LIBS

Abstract

Conventional LIBS suffers from several challenges including high detection limit and low sensitivity. The current approaches include electric field-assisted laser-induced breakdown spectroscopy (EF-LIBS) to study the laser ablation process and characterize the effectiveness of this method on several parameters such as plasma temperature, electron number density, intensity enhancement, and limits of detection. The purpose of the present study is to analyze the improvement in the signal intensity and limits of detection of Copper (Cu), Silver (Ag), and Gold (Au) using EF-LIBS. The laser plasma is generated by focusing a high-power laser beam on gold alloy samples. The intensities of Cu and Ag lines were normalized using the Au line to reduce the statistical errors. Calibration curves were drawn for each element to determine the limit of detection (LOD). The detection sensitivity was enhanced using an external electric field to the axial direction of plasma. The effect of the electric field on plasma parameters, limits of detection, and signal intensities has been studied. It was observed that LODs of Cu and Ag were improved from 14.3 ppm to 4.6 ppm–1.7 ppm and 2.06 ppm respectively with significant enhancement in the emission intensity. The present study demonstrates that EF-LIBS can be utilized for the better detection of precious elements in geological mineralogical and alloy samples. In addition, results showed that the single-shot EF-LIBS is a better choice for precious samples because of a smaller mass ablation against standard LIBS and it is a low-cost setup as compared to other analytical techniques.