纳米金改善激光诱导等离子体探测方法研究

Study on the improvement of laser induced plasma detection method by Au-nanoparticles

针对提高激光诱导击穿光谱技术(LIBS)中等离子体的发射光谱强度的问题,提出一种在铜样品表面沉积金纳米颗粒的方法。在样品表面沉积纳米金颗粒后对铜进行激光诱导击穿(NELIBS),得到NELIBS和LIBS下的发射光谱强度增强因子、信噪比等参数。实验表明,通过在铜样品表面沉积金纳米颗粒的LIBS(NELIBS)可以有效增强等离子体辐射光谱信号强度,铜元素谱线增强因子最高可达8.01,微量元素镁元素谱线增强因子最高为6.01,且增强因子均随激光能量的增加而逐渐减小并趋于稳定;NELIBS可以明显改善信噪比,铜元素在激光脉冲能量为80 mJ时达到最优,镁元素在激光能量为50 mJ时达到最优。对谱线Cu I 521.8 nm和Mg II 279.569 nm进行洛伦兹拟合,并得到半高全宽,发现纳米金颗粒使谱线半高全宽增加,谱线Mg II 279.569 nm的半高全宽增加了165.58%,谱线Cu I 521.8 nm的半高全宽增加了30%。样品中的微量元素因谱线强度低、信噪比差而无法探测到,通过此方法可以有效提高探测能力。

In order to improve the emission spectrum intensity of plasma in laser induced breakdown spectroscopy(LIBS), a method of depositing Au-nanoparticles on the surface of copper samples was proposed. The Au-nanoparticles enhanced LIBS(NELIBS) was deposited on the surface of the sample, and the emission intensity enhancement factor and signal-to-noise ratio(SNR) of NELIBS and LIBS were obtained. Experimental results show that the intensity of plasma radiation spectral signal can be effectively enhanced by depositing Au-nanoparticles LIBS(NELIBS) on the surface of copper samples. The copper element line enhancement factor can reach up to 8.01, and the trace element magnesium element line enhancement factor is up to 6.01. The enhancement factor decreases with the increase of laser energy and tends to be stable. NELIBS can significantly improve the signal-to-noise ratio. The copper element is optimal when the laser pulse energy is 80 mJ, and the magnesium element reaches 50 mJ when the laser energy is optimal. The trace elements in the sample cannot be detected due to the low spectral intensity and poor signal-to-noise ratio. This method can effectively improve the detection capability.