Methods for rapid identification of explosives and their associated compounds at trace level quantities are needed for security screening applications. In this paper, we apply the surface‐enhanced Raman spectroscopy (SERS) to detect and identify traces (as low as tens of pg) of pentaerythritol tetranitrate (PETN), ethylene glycol dinitrate (EGDN), cyclotrimethylene‐trinitramine (RDX) and trinitrotoluene (TNT) using commercially available substrates (Klarite®, Renishaw diagnostics). High quality spectra were achieved within 10 s with a compact Raman spectrometer. Principal component analysis (PCA) of the data was performed to understand what factors affected the spectral variation across the samples. It was found that 76% of the spectral variation was explained by the first three PCs. Score plots for these components showed that the energetic materials can be clearly classified on the basis of SERS spectra also at trace level quantity. Our measurements further demonstrate the potential for using SERS as fast, in situ analytical tool for safety devices, with a sensitivity which competes and, in some cases, overcomes other techniques. Copyright © 2013 John Wiley & Sons, Ltd.

The detection of explosives and their associated compounds for security screening is an active area of research and a wide variety of detection methods are involved in this very challenging area. Surface-enhanced Raman scattering (SERS) spectroscopy is one of the most sensitive tools for the detection of molecules adsorbed on nano-scale roughened metal surface. Moreover, SERS combines high sensitivity with the observation of vibrational spectra of species, giving complete information on the molecular structure of material under study. In this paper, SERS was applied to the detection of very small quantities of explosives adsorbed on industrially made substrates. The spectra were acquired with a compact Raman spectrometer. Usually, a high signal-to-noise (S/N) spectrum, suitable for identification of explosive molecules down to few hundreds of picograms, was achieved within 30 s. Our measurements suggest that it is possible to exploit SERS using a practical detection instrument for routine analysis.

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Surface-enhanced Raman spectroscopy (SERS) measurements on 1,3,5-trinitroperhydro-1,3,5-triazine were performed with a table-top micro-Raman system exciting the analyte with a diode laser emitting at 785 nm. The main Raman features of 1,3,5-trinitroperhydro-1,3,5-triazine were clearly identified, and a careful optimization of acquisition parameters was performed in order to increase the overall sensitivity of the apparatus. The amount of the sampled substance was determined through the analysis of high-resolution scanning electron microscope images of the substrate covered with the residual explosive and resulted to be of the order of few tens of picograms. This value demonstrates the applicability of commercial substrates to the ultrasensitive surface-enhanced Raman spectroscopy detection of explosives, allowing for their identification in real time.