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TATP and TNT detection by mid-infrared transmission spectroscopy

 
: Herbst, J.; Hildenbrand, J.; Wöllenstein, J.; Lambrecht, A.

:
Postprint urn:nbn:de:0011-n-955278 (1.4 MByte PDF)
MD5 Fingerprint: 5b285339f729b321cd4c1df58d534cfd
Copyright 2009 Society of Photo-Optical Instrumentation Engineers. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited.
Erstellt am: 13.7.2010


Andresen, B.F. ; Society of Photo-Optical Instrumentation Engineers -SPIE-, Bellingham/Wash.:
Infrared Technology and Applications XXXV : April 13-17, 2009, Orlando, FL, USA
Bellingham, WA: SPIE, 2009 (SPIE Proceedings Series 7298)
ISBN: 978-0-8194-7564-0
ISSN: 0277-786X
Art. 72983W
Conference "Infrared Technology and Applications" <35, 2009, Orlando/Fla.>
Englisch
Konferenzbeitrag, Elektronische Publikation
Fraunhofer IPM ()
absorption spectroscopy; MIR spectroscopy; explosive detection; QCL; TATP; TNT

Abstract
Sensitive and fast detection of explosives remains a challenge in many threat scenarios. Fraunhofer IPM works on two different detection methods using mid-infrared absorption spectroscopy in combination with quantum cascade lasers (QCL). 1. stand-off detection for a spatial distance of several meters and 2. contactless extractive sampling for short distance applications. The extractive method is based on a hollow fiber that works as gas cell and optical waveguide for the QCL light. The samples are membranes contaminated with the explosives and real background. The low vapor pressure of TNT requires a thermal desorbtion to introduce gaseous TNT and TATP into the heated fiber. The advantage of the hollow fiber setup is the resulting small sample volume. This enables a fast gas exchange rate and fast detection in the second range. The presented measurement setup achieves a detection limit of around 58 ng TNT and 26 ng TATP for 1 m hollow fiber. TATP - an explosive with a very high vapor pressure in comparison to TNT or other explosives - shows potential for an adequate concentration in gas phase under normal ambient conditions and thus the possibility of an explosive detection using open path absorption of TATP at 8 μm wavelength. In order to lower the cross sensitivities or interferents with substances with an absorption in the wavelength range of the TATP absorption the probe volume is checked synchronously by a second QCL emitting beside the target absorption wavelength. In laboratory measurements a detection limit of 5 ppm*m TATP are achieved.

: http://publica.fraunhofer.de/dokumente/N-95527.html