Signal stability of surface-enhanced laser-induced breakdown spectroscopy for microdroplet analysis using a porous silicon substrate

Abstract Surface-enhanced laser-induced breakdown spectroscopy (LIBS) is suitable for the analysis of a small amount of liquid. In this method, a sample solution is dried on a solid substrate and the dry residue is analyzed by LIBS. Porous silicon (Si) loaded with gold nanoparticles is a potential substrate for improving the signal intensity of the surface-enhanced LIBS. In this work, we investigated the position-to-position signal fluctuation of the dry residue in the analysis of a strontium chloride (SrCl2) aqueous solution. A strong Sr signal was stably obtained over the entire surface of the porous Si substrate, while the Sr signal was mainly detected at the periphery of the spread area of the sample solution on a flat Si substrate. The relative standard deviation (RSD) of the Sr signal from 15 laser shots on a single porous Si substrate was ca. 10% and the RSD of the 15-averaged Sr signal from 7 substrates was ca. 10%. The results suggest that the porous Si has great potential for improving both the signal intensity and signal stability.