Scanning electron microscope uses a beam of electrons to form images that reveal the topography and composition of a body. Before being focused on the object, incident electrons have high amounts of kinetic energy. Incident electrons interact with the surface of the specimen, and this interaction is determined by the rate of the acceleration of the incident electrons. Energetic electrons are usually released from the surface of the sample when the incident electrons come into contact with it. The interaction results in the formation of scatter patterns that interpret into the shape, composition, size, and texture of the specimen. Detectors are used to attract the scattered electrons such as the backscattered electrons-rays and secondary electrons.
Backscatter electrons provide images that show the composition of the sample. Diffracted backscatter electrons, on the other hand, determine the orientation and the crystalline structure of the sample (Guido, 30). The x-rays emitted from beneath the surface of the sample can provide information about minerals and elements.
Max Knoll was the first to produce a photo in 1935 using an electron beam scanner with an object-field-with of about 50mm (Morte, 470). This photo showed a channeling contrast. It was not until 1937 when Manfred von Ardenne invented the true microscope. He achieved this scanning through a small piece of raster highly focused demagnified beam of electrons. To achieve magnifications while also eliminating the inherent chromatic aberration, Ardenne had to apply the principle of scanning. Ardenne helped build the first SEM used in magnification in 1938. Headed by Charles Oatley, Cambridge groups spearheaded the marketing of the first “stereoscan” (the first commercial instrument) in 1965 (Dykstra, 223).
Electron microscopy involves focusing electron beams of high energy to study materials with nano-scales of measurement. Electron microscopy enables higher magnification of objects and gives higher resolving power for close objects than light microscopy. Consequently, detailed viewing of very minute objects is possible with them.
SEMs have been applied in the characterization of solid materials in various fields. Scanning electron microscopes can reveal fractures, surface contamination, and variation in the composition of chemical. They are also used in quantitative chemical analysis. Therefore, SME is a very fundamental tool for research in medical science, biology, metallurgy, gemology, and forensic science. Scanning electron microscope gives 3-dimensional black and white images about the composition, morphology, and topography of a body (Gunning, 2).
Works Cited
Busca, Guido. Heterogeneous Catalytic Materials: Solid State Chemistry, Surface Chemistry and Catalytic Behaviour. S.l: s.n., 2014. Print.
Dykstra, Michael J. Biological Electron Microscopy: Theory, Techniques, and Troubleshooting. Boston, MA: Springer US, 1993. Internet resource.
Gunning, Brian E. S, and Martin W. Steer. Plant Cell Biology: Structure and Function. , 1996. Print.
Morte, Asunción, and A Varma. Root Engineering: Basic and Applied Concepts. , 2014. Internet resource.
