http://www.theengineer.co.uk/Articles/Article.aspx?liArticleID=294176
"An emerging technology has helped researchers from the Argonne National Laboratory to develop sensors they say can quickly and effectively detect chemical, biological, nuclear and explosive material. A spectroscopic technique utilising mm/THz frequencies - between microwave and infrared on the electromagnetic spectrum - has enabled the team to detect spectral 'fingerprints' that identify explosives and chemicals. The technology detects the energy levels of a molecule as it vibrates, and the frequency distribution of this energy provides a unique and reproducible spectral pattern - a 'fingerprint' that identifies the material. Supported by the US Department of Defence and NASA, the research achieved three important goals."
