| A novel form of open environment photoacoustic spectroscopy was presented. The technique was first applied toward standoff detection of trace surface residues with concentrations as low as 100 ng/cm2. The maximum standoff distance attained was 50 meters under laboratory conditions. The technique was then utilized in a point sensor geometry at concentrations slightly lower than those achieved in standoff.;In the present work, the accomplishments include the usage of mechanical oscillators to detect pulses of light, standoff and point sensor geometries showing a wide range of applications for the technique, detection of trace chemical and biological residues at the 100 ng/cm2 concentrations, standoff distances of up to 50 meters, and the ability to distinguish target molecules on a variety of real surfaces. The main analyte focus was placed on the detection of explosive and nuclear proliferation compounds including cyclotrimethylenetrinitromine (RDX), trinitrotoluene (TNT), pentaerythritol tetranitrate (PETN), and tributyl phosphate (TBP). Biological compounds were also presented with the goal to distinguish the difference between benign and malignant cells in a standoff manner. |
