Evolution Characteristics of the Laser-Plasma Electron Temperature of Heavy Metal Cr in Liquid Matrix

Using the nanosecond single-pulse laser-induced breakdown-spectroscopy (LIBS) technique, we determine the LIBS spectrum of a mixed solution of soluble compounds as a sample. Based on the LIBS measurement system established and the best experimental parameters, we measure the plasma emission spectrum of some lines of the Cr element. When the ICCD gate delay is measured from 500 to 2500 ns every 500 ns, and the liquid sample flow rate is set in the range of 35 ml · min − 1 − 55 ml · min − 1 with an interval of 5 ml · min − 1 , the partial emission line of the Cr element in the laser plasma is measured, and the Boltzmann oblique line is drawn after the integrated intensity obtained. We calculate the evolution characteristics of the laser-plasma electron temperature with experimental parameters. The results show that the electron temperature values obtained from the intensity of the spectral lines of different elements are consistent with each other, indicating the reliability of the experimental measurement data. The range of electron temperature is obtained from the intensity of the Cr element line in the plasma range from 4071.0 K to 5628.4 K. As the flow rate continues to increase, the plasma electron temperature also increases but gradually becomes gentle. We select Cr 357.87 nm as the analytical line in the experiment and measure the particle density ratios of the Cr element in the ground state at different ICCD gate delays and sample flow rates. It provides experimental parameter support for further LIBS quantitative analysis of trace heavy metal elements in a liquid matrix.