A Novel Method for Remotely Detecting Trace Explosives

Events in recent years have led to an increased need for improvements in our abilities to detect explosives. In numerous situations, the capability to detect explosives sensitively, accurately, and rapidly could have great benefit to national security both at home and abroad. Some of the homeland situations that would benefit from improvements in explosives detection include screening passengers and luggage at airports and other sensitive locations, and screening vehicles and people along the perimeters of high-value installations such as federal buildings. Abroad, the improvised explosive device (IED) problem is clearly in need of creative solutions to mitigate the devices' very damaging effects. Much research has been conducted to help solve these problems; however, it is unlikely that any one solution will suffice. If we view the problem of explosive devices as a timeline, from the initial planning to construction of the devices and ultimately to their detonation, we can see that it is preferable to detect the activities as early in the process as possible. The term " left of boom " derives from displaying the explosives creation-to-detonation timeline from left to right and is sometimes used to refer to the concept of early explosives detection. Figure 1 shows a graphical representation of this process. To address these concerns, we have begun several efforts to both understand and help solve the difficult problem of explosives detection. In particular, we are focus-ing on a solution for rapid and remote detection of trace amounts of explosives, with the idea that such a capability would significantly improve our ability to respond left of boom. As we discuss later, bomb making is a messy process The development of a technique with the ability to detect trace quantities of explosives at a distance is of critical importance. In numerous situations when explosive devices are prepared, transported, or otherwise handled, quantifiable amounts of the explosive material end up on surfaces. Rapid detection of these chemical residues in a noninvasive standoff manner would serve as an indicator for attempts at concealed assembly or transport of explosive materials and devices. We are investigating the use of a fluorescence-based technique to achieve the necessary detection sensitivity.