Raman/LIBS Aid Explosives Detection

Using a novel hybrid sensor system, Spanish scientists have used both Raman and laser-induced breakdown spectroscopy (LIBS) simultaneously for the instant, remote standoff analysis of explosive materials. Because the new system allows complementary molecular identification and abundance information to be gathered from two sensing techniques, it represents a powerful analytical tool for the standoff detection of explosives present in trace quantities.

Once completely field-tested, a mobile hybrid sensor system based on this hyphenated spectroscopy approach potentially could be safely used in the detection of explosives residues left, for example, by human fingerprints on surfaces such as car door handles from distances up to 50 m. It could also be used to check for explosives hidden within parked vehicles by taking measurements through windscreens and windows.

The hybrid detection system was developed at the University of Malaga by a team led by Prof. José Javier Laserna. By integrating two Shamrock SR303i spectrometers and iStar intensified CCDs made by Andor Technology of Belfast, Northern Ireland, along with a Cassegrain telescope and a frequency-doubled 532-nm Nd:YAG laser emitting nanosecond pulses, Laserna’s team made simultaneous acquisitions from the same sample of Raman (molecular information) and LIBS spectra (multielemental information) for 4-mononitrotoluene (MNT); 2,6-dinitrotoluene (DNT); 2,4,6-trinitrotoluene (TNT); cyclotrimethylenetrinitramine (RDX); C4 and H15 (both plastic explosives containing 90 percent and 75 percent of RDX by weight, respectively); and Goma2-ECO (Spanish denominated dynamite-class high explosive).

“The Andor iStar iCCD detectors played a vital role in allowing us to develop this new mobile standoff detection system, since their sensitivity allowed us to work with exceedingly low light levels,” Laserna said. “Furthermore, their refresh rates meant we could analyze spectral information at rates in excess of 10Hz and, therefore, perform simultaneous Raman and LIBS spectroscopy in real time.”

According to Laserna, their next development stage will include the integration of chemometric tools and data fusion strategies to further enhance the systematic analysis capabilities of the new mobile sensing system.

For more information, visit: www.andor.com