Minimizing matrix effect in uranium polymetallic ores by orthogonal non-confocal femtosecond-nanosecond laser induced breakdown spectroscopy

To mitigate the negative impact of the matrix effect on the quantification in uranium polymetallic ores using laser induced breakdown spectroscopy (LIBS), we employed orthogonal non-confocal femtosecond-nanosecond (fs-ns) LIBS to minimize matrix effects. The fs pulse laser pre-ablates to form aerosol particles, which are subsequently broken down by the following ns pulse laser and emitted atomic spectra. The dynamic characteristics were recorded using the time-resolved pump-probe shadowgraph technique. The relative sensitivity factors (RSFs) of Dy, Th, Nb, and Y obtained by fs-ns LIBS are more stable, with correlation coefficients ( r ) of the fitted curves all above 0.977. For ns-LIBS, the values of r were 0.827, 0.63, 0.947, and 0.975, respectively. When the characteristic spectral line Th I 330.42 nm was selected to predict the Th concentration, for fs-ns LIBS and ns-LIBS, the regression coefficients (R 2 ) were 0.91 and 0.47, and the relative errors were 8.14% and 22.02%, respectively. This confirms that fs-ns LIBS may effectively minimize matrix effects, improve the accuracy of elemental quantification, and even overcome the shortage of matrix-matched standard samples.