Abstract. High explosives (HE) represent a high risk to the safety and health of the general population. Therefore, there is an ongoing demand for methods of analysis with limits of detection at trace levels for these hazardous chemicals. Since human hair is one of the main physical attributes of our bodies, the interaction of hair surfaces with HE can be of critical importance in forensic and security applications. Noninvasive in situ approaches such as spectroscopic methods are preferred for elucidating these interactions. Among the spectroscopy-based methodologies, those based on Raman scattering are often favored because the sharpness of the vibrational signals facilitates the precise location of the peak maxima and enables more precise determination of the band shifts due to intermolecular interactions. This preliminary study is based on the detection of the HEs 2,4,6-trinitrotoluene (TNT), 1,3,5-trinitroperhydro-1,3,5-triazine (RDX), and pentaerythritol tetranitrate (PETN) on human hair strands by RS. Raman spectral libraries obtained with a 660-nm laser excitation line were generated for black, bleached, and natural gray hair using direct deposition of PETN, TNT, and RDX. Results obtained were confirmed using portable systems operating at 785 and 1064 nm. Spectral data were preprocessed to correct a high fluorescence background exhibited by the samples due to the indole groups and melanin present in hair. Despite the high fluorescence levels that characterized all the samples, the vibrational signatures that identify the presence of the HEs studied could be detected once the optimum acquisition parameters were established. Among the three hair types studied, gray hair was the best substrate to observe the vibrations of HE crystals on hair. A method limit of detection of 2 ± 1 ng was estimated from image analysis of the HE crystals observed and confirmed as ∼3 ± 1 ng using spectroscopic analysis.

中文翻译：

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人发上高爆炸药的拉曼散射检测

摘要。高爆炸药 (HE) 对普通人群的安全和健康构成高风险。因此，对这些危险化学品的痕量检测限的分析方法存在持续需求。由于人的头发是我们身体的主要物理属性之一，头发表面与 HE 的相互作用在法医和安全应用中至关重要。首选非侵入性原位方法，如光谱方法，以阐明这些相互作用。在基于光谱的方法中，那些基于拉曼散射的方法通常受到青睐，因为振动信号的锐度有利于峰值最大值的精确定位，并且能够更精确地确定由于分子间相互作用引起的带移。本初步研究基于检测人发上的 HEs 2,4,6-三硝基甲苯 (TNT)、1,3,5-trinitroperhydro-1,3,5-triazine (RDX) 和季戊四醇四硝酸酯 (PETN)股由 RS。使用 PETN、TNT 和 RDX 的直接沉积为黑色、漂白和自然白发生成了使用 660 nm 激光激发线获得的拉曼光谱库。使用在 785 和 1064 nm 下运行的便携式系统证实了获得的结果。由于头发中存在吲哚基团和黑色素，光谱数据被预处理以校正样品表现出的高荧光背景。尽管所有样品都具有高荧光水平，但一旦建立了最佳采集参数，就可以检测到识别所研究 HE 存在的振动特征。在研究的三种头发类型中，白发是观察头发上 HE 晶体振动的最佳基质。根据观察到的 HE 晶体的图像分析估计 2 ± 1 ng 的方法检测限，并使用光谱分析确认为 ~3 ± 1 ng。