Abstract: A simple optical layout for a grazing angle probe mount that allows coupling to a mid-infrared (MIR), laser-based spectrometer is provided. The assembly enables doing reflectance measurements at high incident angles. In the case of optically thin films and deposits on MIR reflective substrates, a double pass effect, accompanied by absorption by the chemicals or biological samples deposited in an Infrared Reflection-Absorption Infrared Spectroscopy (IRRAS) modality is achieved. The optical system includes a probe that allows the passage of MIR light through the same sampling area twice. Initially, the infrared beam produces a spot on the surface, and then the light is returned in back reflection to the sample surface producing a new little slightly larger spot onto the selfsame position.

Abstract: The invention provides the use of instrumentation and methods for the rapid separation, detection, and identification of chemical compounds by coupling a well-established chromatographic separation science technique, TLC, with mid-infrared (MIR) QCLS for the analysis of explosives, pollutants, and other threat chemicals. The stationary phases were silica gel adhered to metallic aluminum supports. The mobile phases consisted of organic solvents and their mixes. The position and spot diameter of the TNT samples on the plate containing the adsorbent silica film were measured and compared before and after the chromatographic runs. The MIR vibrational identification of TNT was performed through reflectance measurements using a widely tunable three-diode source. The symmetric stretching vibration of the nitro group [?s(NO2)] centered at approximately 1350 cm?1 and the asymmetric stretching vibration of the nitro group [?as(NO2)] at approximately 1530 cm?1 were clearly observed.

Abstract: The invention described relates to the synthesis of gold nanorods in high concentrations in a single batch and their use in detection of nitroexplosives using Surface Enhanced Raman Spectroscopy (SERS). The nanoparticle suspensions were stable up to a month after preparation. The aggregated nanorods have a strong SERS effect for nitroexplosives (3,5-dintro-4-methylbenzoic acid and 2,4,6-TNT) with sensitivity of 5.0 pg in a few seconds. The results obtained in numerous tests demonstrated a high reproducibility that makes aggregated nanorods very attractive substrates for defense and security applications.