We demonstrate single-beam coherent anti-Stokes Raman spectroscopy (CARS), for detecting and identifying traces of solids, including minute amounts of explosives, from a standoff distance (>50 m) using intense femtosecond pulses. Until now, single-beam CARS methods relied on pulse-shapers in order to obtain vibrational spectra. Here, we present a simple and easy-to-implement detection scheme, using a commercially available notch filter that does not require the use of a pulse-shaper.
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We thank S. Soria for providing the RPCS filter and the AFM image used in this work. We also thank E. Grinvald, G. Elazar, and G. Han for invaluable help. This work was supported in parts by DHS Center of Excellence of Explosives Detection, Mitigation, Response and by NATO Project No. SfP-983789. J.M.L. was supported by the European MC-ITN FASTQUAST.