Laser-induced Breakdown Spectroscopy Enhancement Characteristic And Quantitative Analysis Research

Laser-induced breakdown spectroscopy(LIBS)is a kind of qualitative and quantificational matter analysis technology using emission spectroscopy.Because traditional LIBS technology has shortcomings such as low detection sensitivity and high spectral background noise,which affect the accuracy and precision of substance detection.It is found that these defects can be effectively improved by enhancing the spectral intensity.Aiming at the requirements of LIBS technology to enhance spectral signal and improve detection accuracy,two methods of cavity confinement LIBS(CCLIBS)and plane mirror combined with nanoparticle enhanced LIBS(PM+NELIBS)were used.The changes of plasma parameters and quantitative analysis accuracy under traditional and enhanced LIBS were studied.The cylindrical cavities of plastic and aluminum with diameter of 5mm and 6mm and height of 1-5mm were fixed on the surface of brass sample.The enhancement factor and the signal-to-background ratio(SBR)of Cu I 515.32nm characteristic spectral line were calculated and the time evolution characteristics of electron temperature and electron density were analyzed.The experimental results show that when the height is 4mm and the diameter is 5mm,the aluminum cavity has the most obvious enhancement effect,and the enhancement factor reaches 28.29,the SBR reaches 44.03.In addition,the electron temperature and electron density reach the maximum values at 1?s,which are 7748.10K and 5.44368×10¹⁵cm^-3,respectively.The Au-nanoparticles(Au-NPs)with different particle sizes(10nm,20nm,30nm,40nm)were coated on the surface of the stainless steel sample,and the optimal enhancement spectral particle size was determined to be 20nm.Three plane mirrors combined with 20nm Au-NPs were applied to laser ablation stainless steel sample,and the changes of the spectral enhancement factor and SBR were compared in the four conditions of LIBS,PMLIBS,NELIBS,PM+NELIBS.The experimental results show that the enhancement factor and SBR reach the maximum values under the condition of PM+NELIBS,which are 2.98 and 10.04,respectively.Five kinds of standard stainless steel samples were laser induced breakdown under three conditions of traditional LIBS,Al CCLIBS and PM+NELIBS.The calibration models of Ni element were built by using external standard method and internal standard method,and the limits of detection of elements in alloy samples were analyzed.The experimental results show that the degree of accuracy and stability of the calibration model are the highest when using internal standard method,R²reaches 0.996,and RMSEP is only 0.0746,and the Ni element detection limit reaches minimum value of 3.505?g/g under the condition of PM+NELIBS.