Subsurface contaminant monitoring by laser fluorescence excitation-emission spectroscopy in a cone penetrometer probe
- Tufts Univ., Medford, MA (United States). Dept. of Chemistry
A laser-induced fluorescence (LIF) excitation-emission matrix (EEM) probe has been developed for subsurface monitoring of fluorescent organic contaminants. The fourth harmonic of a flashlamp-pumped Nd:YAG laser (at 266 nm) is used to pump a Raman shifter. Up to ten laser beams (in the wavelength region of 258 to 379 nm) from the Raman shifter are launched into optical fibers that conduct the light to the probe near the tip of the cone penetrometer. The fluorescence emission is excited through ten separate sapphire windows and collected by ten collection fibers that conduct the fluorescence to a spectrograph/CCD detection system. This probe allows real-time collection of LIF-EEMs of contaminants adsorbed on solids or dissolved in groundwater. LIF-EEMs provide a substantial amount of spectral information that can be used to determine the composition and quantity of contaminants in soils. The system was tested and calibrated in the laboratory. Spectra of different organic contaminants were measured in aqueous solutions, in organic solvents, and in different types of soils.
- OSTI ID:
- 153186
- Report Number(s):
- CONF-9506232--; ISBN 0-8194-1862-5
- Country of Publication:
- United States
- Language:
- English
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