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Electron Microscope Definition

Electron Microscope is a scientific instrument constructed in 1931, aimed at better magnification of very small objects. The principle behind electron microscopy is based on the electron wave theory of quantum mechanics. The creation of electron microscope paved way to the possibility for high magnifications, thus, making it a valuable invention for scientific research, according to the Nobel Foundation.

  1. History

    • The first working model of electron microscope is attributed to Ernst Ruska and Max Knoll. In 1928, Prof. Knoll assigned Ruska the task to create lenses that would focus electron beam. By 1931, Ruska successfully created two specially designed magnetic coils that focused electron beam for magnification.

    Theory

    • The theory of electron microscopy evolved from quantum mechanics; the study of electromagnetic fields and electrically charged particles. In the 20th century, electron microscopy theory was developed to explain small-scale phenomena such as electron movements. In 1924, French physicist Louis de Broglie hypothesized that electrons exhibit wave-like movements. This hypothesis paved way to wave mechanics, which suggested that electron waves might be utilized to create high magnifying microscopes.

    Definition

    • Electron microscope (EM) is a type of microscope that utilizes electron beam to magnify very small objects, such as DNA sequences and cell structures. The common types of electron microscope are transmission electron microscope (TEM), scanning electron microscope (SEM), Reflection electron microscope (REM), and Scanning Transmission electron microscope (STEM). These and several other EMs varies on magnification levels but is based on the same principle of using electron beam for magnification.

    Function

    • Electron microscopes function by magnifying and manifesting an object's topography, morphology, composition and crystallographic information. Topography is an object's physical feature (how it looks), morphology pertains to shape and size, composition pertains to chemical properties and crystallographic information refers to an object's atomic arrangement, such as conductivity.

    Mechanism of Action

    • EM's mechanism of action can be summarized in four steps: (1) formation of a stream of electrons, (2) confinement of the stream to form a focused beam, (3) adjusting the focus of beam via magnetic lens and (4) interaction of the beam and the object of interest, which is then transformed to a magnified image.

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