Field demonstration of a multichannel fiber-optic laser-induced fluorescence system in a cone penetrometer vehicle
✍ Scribed by Sean J. Hart; Yu-Min Chen; Jonathan E. Kenny; Bob K. Lien; Thomas W. Best
- Publisher
- John Wiley and Sons
- Year
- 1997
- Weight
- 486 KB
- Volume
- 1
- Category
- Article
- ISSN
- 1086-900X
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✦ Synopsis
A laser-induced fluorescence system for in situ detection of soil contamination with cone penetrometer technology, capable of collecting three-dimensional fluorescence fingerprints (excitation-emission matrices, or EEMs) as the probe is advanced vertically, has been developed. In this report, we describe a recent field test at Hanscom Air Force Base, Massachusetts, in which we demonstrated successful operation of the system. The system uses a pair of silica-clad-silica optical fibers for each of its channels (eight of which were used in the work described), one to deliver excitation light from the multiwavelength laser excitation source to the sample, and the other to conduct contaminant fluorescence to a grating spectrograph that utilizes a charge-coupled-device detector to record fluorescence intensity as a function of both excitation and emission wavelength. The matrix-formatted field data are displayed as three-dimensional fingerprints of contamination at given push locations and depths; they are also reduced in dimension by summing over one or both wavelength axes and plotting summed fluorescence versus depth to facilitate visualization of the approximate extent of the contaminant plume. Selected EEMs from each push location are examined for characteristic patterns and compared to standard EEMs of pure compounds and fuels.