Detection of Y, La, Yb, and Dy elements in rare earth ores by double-pulse laser-induced breakdown spectroscopy

The sensitivity of double-pulse laser-induced breakdown spectroscopy (DP-LIBS) in the detection of trace elements in samples was confirmed to be superior to that of single-pulse laser-induced breakdown spectroscopy (SP-LIBS). However, DP-LIBS is not economical because it requires two lasers. A DP-LIBS system based on beam splitting was proposed in this work, and the experimental equipment was used to analyze Y, La, Yb, and Dy elements in rare earth ores. The comparison of spectral line intensities and sensitivities of rare earth elements in rare earth ore samples between DP-LIBS and SP-LIBS was studied. The results show that the enhancement of the spectral line signal intensity of DP-LIBS is more than two times compared with that of SP-LIBS. The time evolution of signal intensities of four rare earth element characteristic lines (Y II 437.49 nm, La II 433.37 nm, Yb II 328.94 nm, and Dy II 353.17 nm) was given. The enhancements of signal intensities were found to be due to that the plasma temperature of DP-LIBS is increased by more than 500 K. The limits of detection of Y, La, Yb, and Dy were 40.97, 104.09, 47.13, and 56.25 ppm for SP-LIBS and can be reduced to 21.19, 56.93, 28.69, and 36.41 ppm for DP-LIBS. It is showed that DP-LIBS based on a single Nd:YAG laser can better improve the signal intensity and sensitivity of Y, La, Yb, and Dy elements in rare earth ore samples.