Supersonic jet spectrometry (Review) - Fundamentals and applications to dioxin analysis

Abstract

In supersonic jet spectrometry, a molecule is cooled to several K in the gas phase. By cooling the molecule, it becomes possible to observe a structured excitation or multiphoton ionization spectrum comprising sharp spectral lines. Further, it is also possible to measure a fluorescence spectrum or photo-ionization mass spectrum to identify the chemical species. Therefore, high spectral selectivity is provided in this approach. If necessary, it is possible to combine this method with synchronous scan luminescence spectrometry or a separation technique in order to improve the selectivity. On the other hand, this method allows single-molecule detection, in theory. Thus, supersonic jet spectrometry has both very high selectivity and sensitivity. Recently, an ultrasensitive technique is strongly required for dioxin analysis, and supersonic jet spectrometry is expected to be used for this purpose. However, dioxins consist of various type of compounds having different toxicities and, as a result, a method which is capable of differentiating these compounds is desirable. In addition, due to the very high toxicities of these compo unds, it is necessary to use a sensitive method as well for ultratrace analysis. For these reasons, supersonic jet spectrometry has been developed for successful use in dioxin analysis. The present status concerning the development of this method is also described in this report. © 2001 The Japan Society for Analytical Chemistry.