Enhancing Raman spectrographic sensitivity by using solvent extraction of vapor or particulate trace materials, improved surface scatter from nano-structures on nano-particles, and volumetric integration of the Raman scatter from the nano-particles' surfaces

摘要

This invention is a method to enhance by orders of magnitude accurate, real-time, stand-off detection by a sensor using Raman spectra of one or more trace compounds of interest (particularly explosives, bioterror organisms, or Volatile Organic Compounds). A colloid, whose medium of suspension is a liquid solvent with a weak Raman spectrum and in which are suspended particles of a noble metal that are preferentially nano-sized to maximize the surface-to-mass ratio for each particle, forms an impingement base. A sample of this colloid is air-pumped through a sampling module, exposed to air potentially carrying trace molecules from the compound of interest, then sent to a detection module that subjects the sample to Raman spectroscopy. The result is first corrected to obtain a unique Raman spectra from the trace molecules, then matched against Raman spectra in a database. Extensions include modifying, flushing, further processing, or recirculating the colloid sample.