Table of Contents
International Journal of Spectroscopy
Volume 2012, Article ID 158715, 9 pages
http://dx.doi.org/10.1155/2012/158715
Research Article

Resonance-Enhanced Raman Spectroscopy on Explosives Vapor at Standoff Distances

Department of Energetic Materials, Swedish Defense Research Agency (FOI), 147 25 Tumba, Sweden

Received 23 June 2011; Revised 19 September 2011; Accepted 2 November 2011

Academic Editor: S. Michael Angel

Copyright © 2012 Anneli Ehlerding et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Resonance-enhanced Raman spectroscopy has been used to perform standoff measurements on nitromethane (NM), 2,4-DNT, and 2,4,6-TNT in vapor phase. The Raman cross sections for NM, DNT, and TNT in vapor phase have been measured in the wavelength range 210–300 nm under laboratory conditions, in order to estimate how large resonance enhancement factors can be achieved for these explosives. The results show that the signal is enhanced up to 250,000 times for 2,4-DNT and up to 60,000 times for 2,4,6-TNT compared to the nonresonant signal at 532 nm. Realistic outdoor measurements on NM in vapor phase at 13 m distance were also performed, which indicate a potential for resonance Raman spectroscopy as a standoff technique for detection of vapor phase explosives. In addition, the Raman spectra of acetone, ethanol, and methanol were measured at the same wavelengths, and their influence on the spectrum from NM was investigated.