Electron microscopy light microscope structure

To obtain real-space information about the morphology of polymeric materials, various optical microscopic methods such as OM and CLSM are available (cfr. Chp. 5.3). Use of electrons as a light source for microscopy opens other perspectives [124]. Electron microscopy (EM) provides structural information in both the real and reciprocal space. Electron... 

The classical polarizing light microscope as developed 150 years ago is still the most versatile, least expensive analytical instrument in the hands of an experienced microscopist. Its limitations in terms of resolving power, depth of field, and contrast have been reduced in the last decade, in which we have witnessed a revolution in its evolution. Video microscopy has increased contrast electronically, and thereby revealed structures never before seen. With computer enhancement, unheard of resolutions are possible. There are daily developments in the X-ray, holographic, acoustic, confocal laser scanning, and scanning tunneling micro-... 

As NRA is sensitive only to the nuclei present in the sample, it does not provide information on chemical bonding or microscopic structure. Hence, it is often used in conjunction with other techniques that do provide such information, such as ESCA, optical absorption. Auger, or electron microscopy. As NRA is used to detect mainly light nuclei, it complements another accelerator-based ion-beam technique, Rutherford backscattering (RBS), which is more sensitive to heavy nuclei than to light nuclei. 

A hindrance to the elucidation of membrane structure is, of course, the material itself. Membranes are rather intractable lipoprotein systems. Their lipid, protein, and carbohydrate contents are variable both quantitatively and qualitatively since they cannot be crystallized, a detailed analysis by x-ray diffraction is impossible, and since they do not form solutions, the use of hydrodynamic or light-scattering techniques is quite limited. Electron microscopy has been the major physical method, but it is becoming increasingly clear that the electron microscope, at least at present, is incapable by itself of clarifying membrane structure on the molecular level (47). Despite an extensive literature, there is no general... 

We shall first examine the microscopic techniques which allowed us to study these transformations and to show the striking analogy between the images obtained by optical microscopy in polarized light and by electron microscopy with ultrathin sections, despite the difference of the absorption mechanisms of light and electrons. Once this analogy was established, we sought to use electron microscopy and electron microdiffraction to learn more about the texture and structure of the anisotropic areas. 

In the late nineteenth century, as physics progressed rapidly, J. J. Thomson discovered the electron the invention of the electron microscope followed several decades later. Because the wavelength of the electron is shorter than the wavelength of visible light, much smaller objects can be resolved if they are illuminated with electrons. Electron microscopy has a number of practical difficulties, not least of which is the tendency of the electron beam to fry the sample. But ways were found to get around the problems, and after World War II electron microscopy came into its own. New subcellular structures were discovered Holes were seen in the nucleus, and double membranes detected around mitochondria (a cell s power plants). The same cell that looked so simple under a light microscope now looked much different. The same wonder that the early light microscopists felt when they saw the detailed structure of insects was again felt by twentieth-century scientists when they saw the complexities of the cell. 

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