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Abstract

The interaction of the electron beam with the specimen not only provides information on its ultrastructure, but also on its elemental composition. In principle, the irradiating electron beam (probe) is focussed on the area of interest in the specimen, while the secondary radiation (e.g. X-rays) generated by the interaction with the specimen is processed through a spectrometer to provide information on the kind and amount of the elements present. Today, electron probe X-ray microanalysis (EPXMA) is the most widely used method in biological microanalysis. Also, electron energy loss spectrometry (EELS) acquires more and more attention. It would be beyond the scope of this book to explain the physical principles and the methodology of these analytical methods here, in particular, since there are numerous, well-written reviews on this subject (e.g. Chandler 1977; Hren et al. 1979; Hall and Gupta 1983; Morgan 1985). Rather, we want to discuss the particular importance of cryotechniques in this field and to point out the still existing problems of specimen preparation. Its crucial steps are not only relevant for EPXMA and EELS, but also for other microanalytical techniques such as proton probe X-ray microanalysis and laser probe mass spectrometry.