Comparison of Fresh and Aged TNT with Multiwavelength Raman Spectroscopy

Differences in the Raman signatures of fresh and environmentally aged explosives could allow a warfighter who has identified the presence of trace amounts of explosives to ascertain if the material detected is the remnant of a previous event that has been exposed to the environment for a period of time or is an indication of a current threat. To determine if environmental exposure alters Raman signatures, we examined the signatures of fresh and artificially aged TNT at multiple illumination wavelengths between 420 and 620 nanometers. While the macroscopic differences (such as peak height and line ratios) between the Raman signatures of the fresh and aged samples are either too small or not reproducible enough to use for differentiation, we find that by utilizing an algorithm based on the Pearson correlation coefficient, differentiation can be made between the fresh and aged variants at an accuracy of 82%. The original document contains color images. Prepared in collaboration with Research Support Instruments, Lanham, MD.