Transmission electron basic optics

This chapter describes briefly the basic construction and characteristics of the modern transmission electron microscope and discusses its principal modes of operation. Because the electron microscope is an analogue of the optical (or light) microscope, we also consider briefly the basic features of the optical microscope this will also provide a link with our earlier discussion of the optical principles of image formation by a lens. 

The basical theories, equipments, measurement practices, analysis procedures and many results obtained by gas adsorption have been reviewed in different publications. For macropores, mercury porosimetry has been frequently applied. Identification of intrinsic pores, the interlayer space between hexagonal carbon layers in the case of carbon materials, can be carried out by X-ray dififaction (XRD). Recently, direct observation of extrinsic pores on the surface of carbon materials has been reported using microscopy techniques coupled with image processing techniques, namely scarming tunneling microscopy (STM) and atomic force microscopy (AFM) and transmission electron microscopy (TEM) for micropores and mesopores, and scanning electron microscopy (SEM) and optical microscopy for macropores [1-3],... 

Microscopy is the study of the fine structure and morphology of objects with the use of a microscope. Microscopes range from optical microscopes, which resolve details on the micrometer level, to transmission electron microscopes that can resolve details less than one nanometer across. The size and visibility of the polymer structure to be characterized generally determines which instrument is to be used. For example, the size and distribution of spherulites can be observed by optical techniques, but a study of their internal structure requires electron microscopy. Combinations of the various microscopy techniques generally provide the best insight into the morphology of polymer materials [1]. Table 2.1 shows the basic properties of the different microscopes, for the purpose of comparison. 

Figure 3, Basic concept of intracellular SERS probes Gold nanoparticles are transferred into cells. Aggregates which provide optimum SERS enhancement and are typically utilized in the live cell experiments are shown in the transmission electron micrograph and the schematic drawing. During excitation with laser light in the near-infrared (h VjJ, such gold nanoaggregates provide enhanced local optical fields in their nm-scaled vicinity, leading to surface-enhanced Stokes (h and anti Stokes...

The experimental-theoretical study of mesophase formation in amphiphilic systems emphasizes the basic chemical, physical, and materials science aspects of the systems. The most commonly discussed mesophases, beyond the simple micelles discussed in Chapter 4, are lamellar aggregated micellar (packed in various cubic and hexagonal close-packed arrays), columnar or ribbon phases (rod-shaped micelles stacked in a two-dimensional hexagonal or rectangular array) microemulsions, and the cubic bicontinuous mesophases. The experimental techniques normally used to identify these mesophases are NMR Uneshape analysis, diffusion measurements, smaU-angle neutron and X-ray scattering, and optical texture analyses. In addition, reconstraction of electron density profiles and very low temperature transmission electron microscopy (TEM) have been used to elucidate the details of these mesostractures. 

In TEM, the acceleration voltage applied will determine the velocity of the electrons in the beam to be collimated by the condenser lenses, which also occurs in the SEM. In fact, the basic distinction between SEM and TEM is closely related to the electron beam. It is the intensity of the beam and how it is controlled by optical-electronic column that define much of what can be achieved in scanning analysis or transmission [12]. 

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