Scanning transmission electron microscopy principle

The principle of the scanning transmission electron microscope (STEM) is, at first glance, very different from that of the transmission electron microscope the electrons are focused on a probe scanned on a sample and the transmitted electrons are detected on a scintillator via a collection aperture. There is, however, a so-called reciprocity relationship between transmission electron microscopy and the STEM that can be used to describe image formation using the same formalism and facilitates the understanding of contrast. 

Various interactions between electron beams and the samples are schematically illustrated in Fig. 6. In this section, operating principles and characteristics of scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Auger electron spectroscopy (AES), which are often used for the analyses of corrosion and surface finishing, are described. 

In the present chapter, we discuss the principles and techniques commonly used for observing biological surface structures, including optical microscopy (light microscopy, laser scanning confocal microscopy), electron microscopy (scanning electron microscopy, transmission electron microscopy), and scanning probe microscopy. We describe and contrast the sample preparation of each technique. Quantitative data analysis as well as the limitations of each technique is also addressed. 

The sizing methods involve both classical and modem instrumentations, based on a broad spectrum of physical principles. The typical measuring systems may be classified according to their operation mechanisms, which include mechanical (sieving), optical and electronic (microscopy, laser Doppler phase shift, Fraunhofer diffraction, transmission electron miscroscopy [TEM], and scanning electron microscopy [SEM]), dynamic (sedimentation), and physical and chemical (gas adsorption) principles. The methods to be introduced later are briefly summarized in Table 1.2. A more complete list of particle sizing methods is given by Svarovsky (1990). 

In principle, the TEM can be operated in a scanning mode, too— this modification is called transmission scanning electron microscopy (TSEM). 

In this chapter, the principle, recent developments, and selected applications of some commonly used experimental techniques for characterizing semicrystalline polymers are described.These techniques include optical microscopy, electron microscopy (transmission and scanning), atomic force microscopy, nuclear magnetic resonance, diffraction and scattering (X-ray, neutron, and... 

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