Principal Investigator Harold Hemond
Measurement of volatile organic contaminants in groundwater is costly due to the cost of drilling, and the delay and expense of obtaining samples and taking them to fixed laboratory locations. Driveable probes based on LIF may overcome these problems to a degree, but are hindered by the use of large above-ground lasers and the associated problem of propagating ultraviolet excitation to the subsurface via optical fiber, which is lossy in the UV range. In this project we developed a probe based on a Q-switched microlaser developed at MIT's Lincoln Labs. This laser provides short-duration (order of 200ps) pulses ideal for exploiting fluorescence lifetime as an identification tool, and is small enough to be contained within the driveable probe. In addition, the probe has been characterized with respect to the effects of different soil types and textures, and a model that predicts correction factors for different soils has been developed.