Improving quantitative accuracy in surface-enhanced LIBS via spatially extended plasma collection

Abstract

Surface-enhanced laser-induced breakdown spectroscopy (SENLIBS) enhances liquid analysis sensitivity by preconcentrating analytes on substrates, yet the coffee-ring effect (CRE) causes uneven elemental distribution and plasma fluctuations, reducing quantitative accuracy. This study proposes an optical-collection-side method by implementing a spatially extended plasma collection system to improve the quantitative accuracy of SENLIBS. Through Zemax simulations and LIBS experiments, the method reduces plasma fluctuations via spatial averaging, significantly improving spectral stability and quantitative accuracy over point collection. The results showed that the relative standard deviation of the Cr I 425.44 nm intensity decreased from 10.80% to 9.38%, while quantitative accuracy improved by 68.29%. This work demonstrates that optimizing the collection geometry to match plasma spatial characteristics offers a novel pathway to mitigate CRE-induced inaccuracies in SENLIBS.