Single Fiber Measurements for Remote Optical Detection of TNT (trinitrotoluene)
Abstract
Single fiber optical measurements have been used to follow changes in the color of an initially clear poly(vinyl chloride) (PVC) membrane, which reacts with aqueous 2,4,6-trinitrotoluene (TNT) to form a colored product that absorbs strongly at 500 nm. Attempts to make this measurement via the effect of the colored product on the emission spectrum of a fluorophor incorporated into the PVC membrane were unsuccessful. However, single fiber absorption measurements were successful. Refractive index matching and a reflector behind the membrane to increase reflected intensity were essential to keeping the stray light levels small relative to the signal of interest. To compensate for drift, the reflected intensity at 500 nm is measured relative to the reflected intensity at 824 nm, a wavelength where intensity is not affected by color formation in the membrane. The rate at which the ratio of intensity at 500 nm to intensity at 824 nm increases is a function of TNT concentration. It is estimated that TNT levels below 0.10 ppm can be measured by this technique.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1989
- Accession Number
- ADA209995
Entities
People
- Donald C. Sundberg
- W. R. Seitz
- Yunke Zhang
Organizations
- University of New Hampshire