Imaging and Microanalysis by Electron Spectroscopy

Abstract

The dominant strength of electron microsopy is the ability to produce high resolution images. For stained biological specimens in bright field this means a biologically interpretable detail of about 2 nm, limited by the Niquist sampling criterion referred to the size of the heavy metal ion stain. For thin unstained specimens, a compromise is struck between enough electron exposure for good counting statistics and a sufficiently low dose to limit radiation-induced structural alterations (Rose, 1977). Here an interpretable resolution of 0.3–0.5 nm has been reached (Ottensmeyer et al., 1975; Ottensmeyer et al., 1977; Andrews & Ottensmeyer, 1982). For individual heavy atoms and for crystalline specimens in materials science, the limit is the resolving power of the objective lens (Henkelman & Ottensmeyer, 1971; Crewe et al., 1970; Uyeda et al., 1978).