激光诱导击穿光谱与拉曼光谱技术在危险物检测中的研究进展

Progress in Laser Induced Breakdown Spectroscopy and Raman Spectroscopy for Hazardous Material Detection

炸药、生物及化学危险物检测在反恐和公共安全领域具有重要应用价值,也是目前亟需解决的问题。激光诱导击穿光谱技术利用高能激光脉冲诱导材料产生等离子体,通过探测等离子体辐射光谱从而分析其组成成分。拉曼光谱技术是基于非弹性光散射的一种光谱检测方法,可以反映分子的振动信息。由于它们都具有快速和非接触遥测的优点,成为最有发展潜力和应用前景的危险物检测技术。介绍了激光诱导击穿光谱、拉曼光谱以及二者联合探测技术在危险物检测中的国内外发展现状,并对各自的优缺点进行了分析。激光诱导击穿光谱信号强、实时性好,但重复性差、基底效应影响显著,在判别组成元素相同而分子结构不同的危险物和干扰物时面临巨大挑战。拉曼光谱能够提供被测物的分子信息,适合于鉴别有机危险物,但信号弱、受荧光干扰大、检测低浓度样品及分析混合物的能力弱,外场使用时受周围杂散光以及环境变化的影响大。将这两种光谱探测技术相融合,发挥各自的优点,可以有效地提高探测危险物的准确度。但两种光谱联合探测系统结构和数据处理复杂,成本高,还有许多技术难点亟需解决。文章最后,对危险物激光诱导击穿光谱和拉曼光谱研究的前景进行了展望。

In recent years,terrorist attacks utilizing explosives and public safety incidents related to chemical and biological hazards have caused a large number of casualties and property losses.Thus,it is urgent to develop techniques for these hazardous materials detection.Laser-induced breakdown spectroscopy（LIBS）is a spectroscopic analysis technique which uses the light emitted from a laser-induced plasma to determine the composition of the sample based on plasma emission intensities.Raman spectrum can reflect the molecular characteristics of the materials to be measured,and it is widely used in the substances detection and identification.As laser-based spectroscopies,LIBS and Raman spectroscopy are the only currently viable techniques that can be utilized to sense trace amounts of hazardous materials such as explosives and chemical/biological agents at standoff distances because of their intrinsic capability for minimally destructive,in-situ and standoff detection.Therefore,they have gained considerable attention recently.The recent research progresses in hazards detection based on LIBS and Raman spectroscopy are reviewed in this paper.The advantages of LIBS include strong signal intensity,real-time,and the high sensitivity of detection.However,LIBS is subject to poor reproducibility and undesirable matrix effects and hard to discrimate between organic dangerous substances and interferents with the same elements and different molecular structure.Unlike LIBS which provides information on the relative elemental content of molecules within the laser plasma,Raman scattering measures the molecular vibration frequencies and offers the information on the molecular composition of the sample and is suitable for distinguishing organic hazards from organic interferents.One drawback with Raman spectroscopy is the weakness of signal intensity,which makes it sensitive to ambient light and fluorescence.Therefore,integrating LIBS with Raman spectroscopy can provide complementary information and it has the potential to become a useful analytical tool for hazardous materials detection.We emphasize the development of fused LIBS-Raman sensor system for standoff explosive detection in this review.However,combined analysis systems with LIBS and Raman spectroscopy have their own problems such as high cost,complicate structure and data processing,and so on.Further studies on the improvement of detectability of LIBS-Raman combined system for trace hazard detection,the exploitation of strategies for reducing the spectral variability and fusing the data of LIBS and Raman spectroscopy,and the robustness under changing ambient environment conditions need to be further developed.This review compares currently used LIBS,Raman and LIBS-Raman combined techniques for hazardous materials standoff detection.Some prospects of the development of LIBS and Raman spectroscopy for hazards detection are also discussed at the end of the review.