Ultraviolet Resonant Raman Enhancements in the Detection of ...

Figure 2. Vapor Phase Concentration of common explosives as a function of
temperature. The solid lines indicate experimental values (From: [6]).
In addition to the extremely low concentration of explosive molecules present in
the gas phase under normal conditions, nitrogen based high explosives have a tendency to
rapidly condense onto aerosols or solid surfaces rather than remain in the vapor phase
further hindering detection efforts.
Canines have an exceptionally acute sense of smell and have typically been the
gold standard for explosive vapor detection, however some trace detection systems have
recently demonstrated improved sensitivities over canine detection by detecting sub-
picogram quantities of select explosives [8]. Even with this exceptional sensitivity, it is
difficult to detect explosive vapors using a point sensor at distances greater than a few
meters. Sometimes favorable wind conditions can extend the range of explosive vapor
detection, however, localizing such sources from turbulent plumes over extended
distances with point sensors has not been demonstrated to date.
8