Abstract
Raman spectroscopy is an analytical technique with vast applications in the homeland security and defense arenas. The Raman effect is defined by the inelastic interaction of the incident laser with the analyte molecule’s vibrational modes, which can be exploited to detect and identify chemicals in various environments and for the detection of hazards in the field, at checkpoints, or in a forensic laboratory with no contact with the substance. A major source of error that overwhelms the Raman signal is fluorescence caused by the background and the sample matrix. Novel methods are being developed to enhance the Raman signal’s sensitivity and to reduce the effects of fluorescence by altering how the hazard material interacts with its environment and the incident laser. Basic Raman techniques applicable to homeland security applications include conventional (off-resonance) Raman spectroscopy, surface-enhanced Raman spectroscopy (SERS), resonance Raman spectroscopy, and spatially or temporally offset Raman spectroscopy (SORS and TORS). Additional emerging Raman techniques, including remote Raman detection, Raman imaging, and Heterodyne imaging, are being developed to further enhance the Raman signal, mitigate fluorescence effects, and monitor hazards at a distance for use in homeland security and defense applications.
Highlights
There are a number of factors driving research, development, and acquisition of new technologies for detecting chemical, biological, radiological, nuclear, and explosive (CBRNE) threat materials
The increasing number of sensors in the field, combined with the general logistical burden to soldiers and emergency responders, is International Journal of Spectroscopy driving the need for the convergence of sensor capabilities and for detectors that can identify a wide range of threats agents
This paper addresses the applicability of a particular laser-based optical technique, Raman spectroscopy, to emerging CBRNE detection needs
Summary
There are a number of factors driving research, development, and acquisition of new technologies for detecting chemical, biological, radiological, nuclear, and explosive (CBRNE) threat materials. As the potential for Cold War-style engagements of massed armies with large quantities of weaponized chemical and biological agents receded, the need has increased to defend against and deter small-scale attacks of increasingly toxic emerging chemical and biological (CB) agents from rogue states, nonstate parties, or terrorist groups. This change in the CB threat has been accompanied by the expanding use of improvised explosive devices (IEDs) by adversaries and the increasing need to detect explosives left-of-boom, to reduce IED casualty rates. This paper addresses the applicability of a particular laser-based optical technique, Raman spectroscopy, to emerging CBRNE detection needs. Techniques that do not alter the physics of Raman detection and only enhance the signal by unique optics are discussed in the application section
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