Gas Analysis by Computer-Controlled Microwave Rotational Spectrometry

Abstract

Microwave rotational spectrometry has inherently high resolution and is thus nearely ideal for qualitative gas mixture analysis. Quantitative gas analysis is also possible by a simplified method which utilizes the ease with which molecular rotational transitions can be saturated at low microwave power densities. This article describes a computer-controlled microwave spectrometer which is used to demonstrate for the first time a totally automated analysis of a complex gas mixture. Examples are shown for a complete qualitative and quantitative analysis, in which a search of over 100 different compounds is made in less than 7 min, with sensitivity for most compounds in the 10 to 100 ppm range. This technique is expected to find increased use in view of the reduced complexity and increased reliability of microwave spectrometers and because of new energy-related applications for analysis of mixtures of small molecules.