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C. Gasser, Engelene Chrysostom, B. Zachhuber, B. Lendl:
"Stand-off SORS: Spatial Offset Raman Spectroscopy";
Poster: IRDG Spring Meeting Vienna, Wien; 24.04.2014 - 25.04.2014; in: "Program & Poster Abstracts", (2014), 1 S.

We present a method for the stand-off detection (at a distance of 12 meters) of potentially hazardous materials concealed in containers or hidden behind opaque layers using a combination of stand-off Raman spectroscopy and Spatial Offset Raman Spectroscopy (SORS). This combination makes it possible to detect chemicals concealed in containers from a distance where a potential danger to the operator is reduced or prevented. SORS enables the detection of deeper layers of a sample by placing the collection optics at a position different (spatially offset) to the excitation spot on the sample surface. In our experimental system, stand-off Raman spectra at distances up to 12 m at different spatial offsets up to 40 mm away from the incident laser excitation were collected using a telescope and an iCCD. By merging SORS with stand-off Raman spectroscopy, it was possible to detect liquid (isopropanol) as well as solid analytes (sodium chlorate) in opaque or white containers. Furthermore, the content of fluorescent containers, which is difficult, if not impossible for conventional stand-off Raman spectroscopy measurements, can now be detected as demonstrated using isopropanol concealed in a plastic bottle covered with a highly fluorescent layer of motor oil. Additionally the power of stand-off Raman spectroscopy as an analytical method to detect different explosives or precursors thereof at a distance of 100 m is demonstrated.

stand off Raman, SORS. spatially offset