Electron Microscope Research Paper

Electron microscopes are scientific microscopes which utilizes a beam of accelerated electrons to get a detailed image of thin sections of a sample. There are two different types of the electron microscope, the first being a transmission electron microscope (TEM) and the scanning electron microscope (SEM). While both the scanning electron microscope and the transmission electron microscope work under the same concept, the SEM focuses on the samples surface and composition whilst the TEM will give information about the sample’s internal composition. The electron microscope was invented by electrical engineer Max Knoll and German physicist Ernst Ruska whose goal was to overcome the barrier of higher resolution

In 1937 the firm funded the work of Ernst Ruska, Bodo von Borries, and hired Helmut Ruska (Ernst’s brother) to advance applications for the microscope, especially with regards to biological samples. In 1937, Manfred von Ardenne pioneered the scanning electron microscope. The first practical electron microscope was built in 1938, by Eli Franklin Burton and students Cecil Hall, James Hillier, and Albert Prebus at the University of Toronto. Siemens began to manufacture the first transmission electron microscope (TEM) for commercial markets in 1939. Though modern electron microscopes are capable of up to a power of two million, as scientific instruments, they remain based under the same concept of Ruska’s prototype. In 1986 “for his fundamental work in electron optics, and for the design of the first electron microscope" Ernest Ruska won the Nobel prize in

The types of signals produced by an SEM include secondary electrons, back-scattered electrons (BSE), characteristic X-rays, light (cathodoluminescence) and transmitted electrons. Secondary electrons are generated as ionization products. They are called 'secondary' because they are generated by other radiation (the primary radiation). This radiation can be in the form of ions, electrons, or photons with sufficiently high energy, i.e. exceeding the ionization potential. Secondary electron detectors are common in all SEMs. A SEM with secondary electron imaging or SEI can produce very high-resolution images of a sample surface, revealing details less than 1 nm in size. Back-scattered electrons (BSE): they are beam electrons that are reflected from the sample by elastic scattering. BSE are often used in analytical SEM along with the spectra made from the characteristic X-rays. Because the intensity of the BSE signal is strongly related to the atomic number (Z) of the specimen, BSE images can provide information about the distribution of different elements in the sample. Characteristic X-rays: they are emitted when the electron beam removes an inner shell electron from the sample, causing a higher