A proposed form of coherent anti-Stokes Raman spectroscopy shows promise in distinguishing anthrax spores from other organic compounds. Like conventional anti-Stokes Raman techniques, the procedure would apply two laser pulses to heighten coherence in the vibrational states of molecules of interest and a third pulse to extract an anti-Stokes signature.The approach, outlined in the Aug. 20 Proceedings of the National Academy of Sciences, induces maximal ground-state coherence in a sample, which runs counter to conventional anti-Stokes techniques. This could help detect specific organic molecules, such as anthrax, against a broad background of materials.The study was funded by the Defense Advanced Research Projects Agency through the Office of Naval Research. It was conducted at Texas A&M University in College Station with help from scientists in Germany, Czech Republic, Pakistan and Bozeman, Mont.