Researches On The Characteristics Of Plasma Spectrum Induced By Filament-Nanosecond Laser Ablated Soil

With the development of industrialization,the heavy metal pollution in the soil has seriously jeopardized the ecological environment,food safety,the health of residents and the sustainable development of agriculture.Therefore,the problem of heavy metal pollution in soil needs to be solved.It is necessary to carry out on-line detection and quantitative analysis of heavy metal element contents based on laser-induced breakdown spectroscopy.In this paper,the time evolution of filament ablation soil sprayed particles was studied,and then obtained the spectral characteristics of soil plasma induced by filament-nanosecond laser pulse,and the quantitative analysis of heavy metal elements in soils were carried out by filament-nanosecond laser-induced breakdown spectroscopy.In this paper,the dynamic process of filament ablation soil sprayed particles with " the intensity clamping effect" was studied by light scattering method,and the variation of soil spattered particles with time was analyzed.Based on the filament ablated the samples to obtain a stable low-density soil particle source,the nanosecond laser pulse re-ablated to produce a plasma with high electron temperature and low electron density,compressed the LIBS linewidth and enhanced the lines strength at the same time,thereby the LIBS spectrum with high spectral resolution was obtained.Next,the content of heavy metal elements Pb and Cr in soil was analyzed by filament-nanosecond laser-induced breakdown spectroscopy(Filament-ns DP-LIBS)quantitatively.Finally,combined with the calibration curve of given heavy metal element Cr,the content of heavy metal element Cr in soil samples from different geographical regions were measured and tested.According to the soil heavy metal pollution standard of environmental protection department,the pollution elements and pollution levels were judged.The results showed that filament-nanosecond laser induced breakdown spectroscopy(Filament-ns DP-LIBS)was used for soil heavy metal Pb and Cr detection with high accuracy,low detection limit and low detection bias.Therefore,the experimental basis for the on-line and in-situ detection of heavy metal elements in soil was established for the filament-nanosecond laser induced breakdown spectroscopy(Filament-ns DP-LIBS).