Explosive compounds such as RDX, and HMX present significant challenges to optically based sensors. This
difficulty is due in part to the low vapor pressures these compounds possess. One approach for sensing explosives
that circumvents the low explosive vapor pressure problem, involves focusing on the trace amounts of relatively
high vapor pressure impurities that will be present in the vapor signature. In order to effectively detect these volatile
impurities, the spectral signature databases must be readily available. One of our goals therefore, is the generation
of a database of high resolution spectral signatures for these volatile organic impurities. Some rather formidable
spectroscopic measurement challenges have been encountered while working to extend the spectral signature effort
to the 3 micron region. Here we will outline progress to date, with a focus on the volatile organic compounds
formaldehyde, acetaldehyde, nitromethane, acetone, isobutene, and cyclohexanone.
Vapor phase sensing and detection of TNT-based explosives is extremely challenging due in part to the low
vapor pressure of TNT. We believe one effective strategy for optically based sensing of TNT-based explosives involves
focusing not on the spectral signature for pure TNT, but rather on a more volatile series of compounds that are present in
TNT as impurities. To date we have catalogued and reported a number of rotationally resolved infrared transition
frequencies for nitrobenzene, toluene, o-nitrotoluene, and m-nitrotoluene in the 14 micron region. Here we describe the
use of an in-house spectral calibration program that while designed for calibration of Pb-salt diode laser spectra, is quite
general and could be utilized for many spectroscopic detection and/or analysis applications. Finally, a sensing
measurement for a volatile organic impurity related to RDX-based explosives such as C4 is presented and discussed.
One of the technological challenges associated with trace vapor detection of explosive materials are the relatively low
vapor pressures exhibited by most energetic materials under ambient conditions. For example, the vapor pressure for
TNT is ~10 ppbv at room temperature, a concentration near the Limit of Detection for many of the technologies
currently being deployed. In the case of improvised explosive devices, the clandestine nature of the device further
serves to exacerbate the vapor pressure issue. Interestingly, the gold standard in explosives detection remains the trained
canine nose. While there is still some debate as to what the dog actually smells, recent studies have indicated the alert
response is triggered, not by the vapor presence of a specific explosive compound but, by a characteristic bouquet of
odors from chemical impurities used to manufacture and process the explosives. Here we present high resolution
infrared data for several of these volatile organic compounds in the 700 cm-1 region required for real time optical sensing
of energetic materials.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.