Long Wave Infrared Detection of Chemical Weapons Simulants

Phillips, Mark C. ; Taubman, Matthew S. ; Scott, David C. ; Myers, Tanya L. ; Munley, John T. ; Cannon, Bret D.

Pacific Northwest National Laboratory (U.S.)

关键词: Signal-To-Noise Ratio;    37 Inorganic, Organic, Physical And Analytical Chemistry;    Sensitivity;    Simulation;    Detection;   

DOI  :  10.2172/903252
RP-ID  :  PNNL-16557
RP-ID  :  AC05-76RL01830
RP-ID  :  903252

美国|英语

来源: UNT Digital Library

【 摘 要 】

The purpose of Task 3.b under PL02-OP211I-PD07 (CBW simulant detection) was to demonstrate the applicability of the sensor work developed under this project for chemical and biological weapons detection. To this end, the specific goal was to demonstrate the feasibility of detection of chemical agents via that of simulants (Freons) with similar spectroscopic features. This has been achieved using Freon-125 as a simulant, a tunable external cavity quantum cascade laser (ECQCL), and a Herriott cell-based sensor developed at Pacific Northwest National Laboratory (PNNL) specifically for this task. The experimentally obtained spectrum of this simulant matches that found in the Northwest Infrared (NWIR) spectral library extremely well, demonstrating the ability of this technique to detect the exact shape of this feature, which in turn indicates the ability to recognize the simulant even in the presence of significant interference. It has also been demonstrated that the detected features of a typical interferent, namely water, are so different in shape and width to the simulant, that they are easily recognized and separated from such a measurement. Judging from the signal-to-noise ratio (SNR) of the experimental data obtained, the noise equivalent absorption sensitivity is estimated to be 0.5 x 10-7 to 1 x 10-6 cm-1. For the particular feature of the simulant examined in this work, this corresponds to a relative concentration of 50 to 25 parts-per-billion by volume (ppbv). The corresponding relative concentrations of other chemical targets would differ depending on the particular transition strengths, and would thus have to be scaled accordingly.