Stand-off measurements on nitromethane (NM), 2,4-DNT and 2,4,6-TNT in vapor phase using resonance Raman
spectroscopy have been performed. 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 measurements show that the signal is greatly enhanced,
up to 250.000 times for 2,4-DNT and 60.000 times for 2,4,6-TNT compared to the non-resonant signal at 532 nm. For
NM the resonance enhancement enabled realistic outdoor measurements in vapor phase at 13 m distance. This all
indicate a potential for resonance Raman spectroscopy as a stand-off technique for detection of vapor phase explosives.