Emerging chemical threats to homeland security challenge the specificity of sensor-based chemical detectors. As the
number of chemicals to detect increases, the false alarm rates of these sensor-based systems tend to increase and the
usefulness of the detector in real world situations declines. The infrared (IR) absorption spectrum of a material is a
physical constant and highly specific for the molecule of interest. For many years, IR spectra have been used by chemists
to identify unknowns based on comparison with spectra of known materials and to determine the presence of chemical
functional groups through spectral interpretation. IR spectroscopy is well suited for the identification of broad-based
chemical threats. This discussion shall concern the conceptual development of a hand held IR spectroscopy system for
the identification of chemical vapor threats. The discussion shall focus on design tradeoffs where miniaturization is of
paramount importance. Quantitative IR absorption spectra of threat compounds were used to model absorption line
strengths at moderate spectral resolutions. IDLH detection limits targets, acquisition time, etendué, and signal-to-noise
parameters guided the concept design and pathlength of a long path gas cell used in conjunction with a hand held FT-IR
spectrometer.
The feasibility of using IR mapping microspectroscopy to locate and identify a neuroanatomical probe in brain tissue has been demonstrated. Frequency specific IR maps were generated from a latex nanosphere injection site in brain tissue. The 2240 cm-1 vCN absorption band, attributable to the latex, was used as an analytical band.
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