Raman spectroscopy is a powerful technique for material identification. The technique is sensitive to primary and higher
ordered molecular structure and can be used to identify unknown materials by comparison with spectral reference
libraries. Additionally, miniaturization of opto-electronic components has permitted development of portable Raman
analyzers that are field deployable. Raman scattering is a relatively weak effect compared to a competing phenomenon,
fluorescence. Even a moderate amount of fluorescence background interference can easily prevent identification of
unknown materials. A long wavelength Raman system is less likely to induce fluorescence from a wider variety of
materials than a higher energy visible laser system.
Compounds such as methyl salicylate (MS), diethyl malonate (DEM), and dimethyl methylphosphonate (DMMP) are
used as chemical warfare agent (CWA) simulants for development of analytical detection strategies. Field detection of
these simulants however poses unique challenges because threat identification must be made quickly without the
turnaround time usually required for a laboratory based analysis. Fortunately, these CWA simulants are good Raman
scatterers, and field based detection using portable Raman instruments is promising. Measurements of the CWA
simulants were done using a 1064 nm based portable Raman spectrometer. The longer wavelength excitation laser was
chosen relative to a visible based laser systems because the 1064 nm based spectrometer is less likely to induce
fluorescence and more suitable to a wider range of materials. To more closely mimic real world measurement situations,
different sample presentations were investigated.