A new ultrasensitive laser that detects the vibrational frequencies of unique molecules in improvised explosive devices (IED), or roadside bombs, can spot the devices from a distance of 40 feet or more. The weapons are the deadliest threat to troops in Iraq and Afghanistan, accounting for about 60 percent of coalition soldiers’ deaths. A simulated IED emits a firestorm as soldiers in the Iowa National Guard's 1-133 Infantry Battalion experience the concussion and noise of an explosion during theater immersion training at Camp Shelby, Miss. The Iowa unit rounded out the 1st Brigade, 34th "Red Bull" Division of nearly 4000 soldiers now serving in Iraq. (Image: Department of Defense) The laser has output comparable to that of a simple presentation pointer, and yet it has the sensitivity and selectivity to canvas large areas and detect IEDs. Sensing IEDs in the field is extremely challenging because the environment introduces a large number of chemical compounds that mask the select few molecules that one is trying to detect, said Marcos Dantus, chemistry professor at Michigan State University who lead the research. “Having molecular structure sensitivity is critical for identifying explosives and avoiding unnecessary evacuation of buildings and closing roads due to false alarms,” he said. Marcos Dantus, a chemistry professor at Michigan State University, has developed a laser that can detect improvised explosive devices from a distance of 40 feet or more. (Image: MSU) Since IEDs can be found in populated areas, the methods to detect these weapons must be nondestructive. They also must be able to distinguish explosives from vast arrays of similar compounds that can be found in urban environments. This new laser can make these distinctions even for quantities as small as a fraction of a billionth of a gram. The laser beam combines short pulses that kick the molecules and make them vibrate with long pulses that listen and identify the different chords, which include vibrational frequencies that uniquely identify every molecule, much like a fingerprint. The high-sensitivity laser can work in tandem with cameras and allows users to scan questionable areas from a safe distance. “The laser and the method we’ve developed were originally intended for microscopes, but we were able to adapt and broaden its use to demonstrate its effectiveness for standoff detection of explosives,” said Dantus, who hopes to net additional funding to take this laser from the lab into the field. The laser has been shown to work at distances up to about 40 feet, though should be possible at distances of 330 feet. "Beyond that, we need engineers who know how to handle longer distances," Dantus told MSNBC. The research was published in the journal Applied Physics Letters. For more information, visit: www.news.msu.edu