Instrument for Real Time Detection of Volatile Organics and Trace Gases

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Many techniques have been used in the past to measure the concentration of volatile organic compounds in the soil and ground water. Some of these techniques require chemical reactions that result in different molecules that are then sensed optically. Other techniques measure the optical absorption of the species to be detected. In almost all instances, a special instrument must be used for each chemical species. This is both expensive and time consuming. Moreover, as chemical reactions are necessary in some instances and detector sensitivity is poor and noise sources abound in the infrared, the accuracy of some of these systems is suspect. Lasergenics Corporation are proposing to demonstrate the sensitivity and wide applicability of Raman scattering to the detection of ppm or less concentrations of volatile organic compounds. This technique has several advantages over present techniques. As the scattered light is in the visible region of the spectrum, very sensitive photomultipliers can be used. Also few noise sources exist. They will construct a breadboard system and measure the sensitivity of this system for four of the most widespread volatile organic compounds. An argon laser operating at 488 nm will be used as the light source and photon counting will be the detection method.