Instrument for Real Time Detection of Volatile Organics and Trace Gases

过去使用了许多技术来测量土壤和地下水中挥发性有机化合物的浓度。其中一些技术需要化学反应，这些化学反应会产生不同的分子，然后通过光学方式进行感知。其他技术测量待检测物种的光吸收。在几乎所有情况下，每一种化学物质都必须使用一种特殊的仪器。这既昂贵又耗时。此外，由于在某些情况下需要进行化学反应，而且探测器的灵敏度很低，而且红外中存在大量噪声源，因此其中一些系统的准确性令人怀疑。Lasergenics公司提议展示拉曼散射在检测ppm或更低浓度的挥发性有机化合物方面的敏感性和广泛适用性。与目前的技术相比，该技术具有几个优点。由于散射光在光谱的可见光区域，所以可以使用非常灵敏的光电倍增管。噪声源也很少。他们将构建一个面包板系统，并测量该系统对四种分布最广泛的挥发性有机化合物的敏感性。将使用工作在488 nm的Ar激光器作为光源，并采用光子计数的检测方法。

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.