High-sensitivity detection of TNT
- Michael B. Pushkarsky*,†,
- Ilya G. Dunayevskiy*,
- Manu Prasanna*,
- Alexei G. Tsekoun*,
- Rowel Go*, and
- C. Kumar N. Patel*,‡,§
- *Pranalytica, Inc., 1101 Colorado Avenue, Santa Monica, CA 90401; and
- ‡Department of Physics and Astronomy, University of California, Los Angles, CA 90095
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Contributed by C. Kumar N. Patel, November 6, 2006 (received for review October 26, 2006)
Abstract
We report high-sensitivity detection of 2,4,6-trinitrotoluene (TNT) by using laser photoacoustic spectroscopy where the laser radiation is obtained from a continuous-wave room temperature high-power quantum cascade laser in an external grating cavity geometry. The external grating cavity quantum cascade laser is continuously tunable over ≈400 nm around 7.3 μm and produces a maximum continuous-wave power of ≈200 mW. The IR spectroscopic signature of TNT is sufficiently different from that of nitroglycerine so that unambiguous detection of TNT without false positives from traces of nitroglycerine is possible. We also report the results of spectroscopy of acetylene in the 7.3-μm region to demonstrate continuous tunability of the IR source.
Footnotes
- §To whom correspondence should be sent at the ∗ address. E-mail: patel{at}pranalytica.com
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Author contributions: C.K.N.P. designed research; M.B.P., I.G.D., M.P., A.G.T., and R.G. performed research; M.B.P., I.G.D., and C.K.N.P. analyzed data; C.K.N.P. wrote the paper; and M.P. generated algorithms for continuous tuning of the external grating quantum cascade lasers.
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↵ †Present address: Daylight Solutions, 13029 Danielson Street, Suite 203, Poway, CA 92064.
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The authors declare no conflict of interest.
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↵ ¶ TNT samples (commercial grade) were obtained from Naval Air Warfare Center, Weapons Division (China Lake, CA). The pedigree of the samples is unknown.
- Abbreviations:
- CDA,
- clean dry air;
- CW,
- continuous wave;
- EGC,
- external grating cavity;
- FTIR,
- Fourier transform IR;
- PA,
- photoacoustic;
- PAS,
- PA spectroscopy;
- L-PAS,
- laser-based PAS;
- QCL,
- quantum cascade laser;
- RT,
- room temperature.
- © 2006 by The National Academy of Sciences of the USA
