Detection of Explosives using Pulsed Laser Fragmentation andMIRSpectroscopy

Abstract

AbstractWithin the past years, an increasing number of optical techniques for the detection of harmful substances has been investigated on account of the threat of terroristic attacks. Optical technologies have the capability to overcome the problems of extensive sample preparation and long measurement cycles that are known from widely used detection techniques such as mass spectrometry and gas chromatography. The threat of bombings has also produced interest in standoff techniques — in addition to checkpoint applications for screening of persons. Even in this field, optical technologies are well suited: to date, Raman spectroscopy and laser‐induced breakdown spectroscopy (LIBS) seem to be the most promising technologies, but other optical methods are permanently developed. Particularly detection in the midinfrared (MIR) spectral region, providing selective fingerprints of molecules in the range from 3 to 11 µm, has experienced a renaissance with development of new laser sources, detectors, and spectroscopic techniques. In this paper, some comparatively new techniques for the detection of explosives in the MIR spectral range, relying on quantum cascade lasers (QCLs) and photoacoustic spectroscopy (PAS), are presented. Another emphasis is put on the indirect detection of explosives via characteristic decomposition products and their active generation with laser‐induced photodissociation techniques.