Several setups for standoff sensing using vibrational spectroscopy were designed. Two modes of detection were used active and passive mode. In the active mode a quantum cascade laser (QCL) and conventional sources (Globar) were used. In active mode the intensity is extremely dependent on the alignment between the source, the target and the detector. We considered the effect of having the source out of alignment at small to relatively large angular deviations from back reflection (normal incidence or 0°). Several substrates and complex matrices were studied using QCL in order to detect highly energetic material (HEM) and biological agent simulants (BAS). HEM used were RDX, PETN, TNT, TATP and AN; BAS were Escherichia coli, Staphylococcus epidermis and Bacillus thuringiensis. The substrates used were glass, cardboard, travel bags, wood, aluminum and stainless steel. HEMs were mixed in various matrices such as sand, clay, synthetic soils and actual soil. Multivariate statistical routines such as principal component analysis (PCA) and partial least squares analysis (PLS), discriminant analysis (DA) and hyphenated routines (PLS-DA) were applied to recorded spectra. The results show that vibrational techniques investigated are useful for classification, detection and quantification of theses microorganisms and HEM in the types of substrates and matrices studied.
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