Effect of plasma radiation attenuation rate on the uncertainty of LIBS signal and real-time correction method.

The integration process of the spectrometer detector is a critical step in Laser-Induced Breakdown Spectroscopy (LIBS) signal acquisition. However, the influence of plasma radiation attenuation during the integration time on LIBS uncertainty remains unclear. In this study, plasma emission was simultaneously monitored using a combined detection system consisting of an echelle spectrometer with an intensified charge-coupled device (ICCD) and a monochromator with a photomultiplier tube (PMT). Based on this setup, the effect of radiation attenuation rate on spectral line intensity was investigated, and a real-time uncertainty correction method using the attenuation rate was developed. Results show that in repeated independent measurements of a homogeneous sample, the radiation attenuation rate at any wavelength is inversely correlated with spectral line intensity. In contrast, for samples with varying contents of the same element, no statistically significant correlation was found between attenuation rate and elemental content. These findings indicate that the radiation attenuation rate is indeed a factor contributing to LIBS signal uncertainty. Moreover, using radiation attenuation rates as correction coefficients for spectral line intensities reduced the relative standard deviation (RSD) of repeated measurements and improved the coefficient of determination (R²) of calibration curves for gradient-content samples. This work clarifies the relationship between plasma radiation attenuation rate and line intensity, and examines its impact on repeatability and quantitative analysis. The results further refine existing theories and provide valuable insights for the theoretical development and broader application of LIBS technology.