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- Scanning Electron Microscopes
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The Scanning Electron Microscope (SEM) is one of the most
versatile and widely used tools of modern science as it allows
the study of both morphology and composition of biological and
physical materials.
By scanning an electron probe across a specimen, high resolution
images of the morphology or topography of a specimen, with great
depth of field, at very low or very high magnifications can be
obtained. Compositional analysis of a material may also be
obtained by monitoring secondary X-rays produced by the
electron-specimen interaction. Thus detailed maps of elemental
distribution can be produced from multi-phase materials or
complex, bio-active materials. Characterization of fine
particulate matter in terms of size, shape, and distribution as
well as statistical analyses of these parameters, may be
performed.
There are many different types of SEM designed for specific
purposes ranging from routine morphological studies, to
high-speed compositional analyses or to the study of
environment-sensitive materials. The Centre for Microscopy &
Microanalysis presents three particular types of SEM that, in
combination, provide a powerful analytical approach for many
research or quality-control applications.
Additional information available at
"http://www.uq.edu.au/nanoworld/sem_gen.html"
[Summary provided by The University of Queensland]
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| broader |
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| Abstract from DBPedia | A scanning electron microscope (SEM) is a type of electron microscope that produces images of a sample by scanning the surface with a focused beam of electrons. The electrons interact with atoms in the sample, producing various signals that contain information about the surface topography and composition of the sample. The electron beam is scanned in a raster scan pattern, and the position of the beam is combined with the intensity of the detected signal to produce an image. In the most common SEM mode, secondary electrons emitted by atoms excited by the electron beam are detected using a secondary electron detector (Everhart–Thornley detector). The number of secondary electrons that can be detected, and thus the signal intensity, depends, among other things, on specimen topography. Some SEMs can achieve resolutions better than 1 nanometer. Specimens are observed in high vacuum in a conventional SEM, or in low vacuum or wet conditions in a variable pressure or environmental SEM, and at a wide range of cryogenic or elevated temperatures with specialized instruments.走査型電子顕微鏡（そうさがたでんしけんびきょう、英語: Scanning Electron Microscope、SEM）は電子顕微鏡の一種である。電子線を絞って電子ビームとして対象に照射し、対象物から放出される二次電子、（後方散乱電子、BSE）、、X線、カソードルミネッセンス（蛍光）、内部起電力等を検出する事で対象を観察する。通常は二次電子像が利用される。透過電子を利用したものはSTEM（走査型透過電子顕微鏡）と呼ばれる。 TEMでは主にサンプルの内部、SEMでは主にサンプル表面の構造を微細に観察する。 (Source: http://dbpedia.org/resource/Scanning_electron_microscope) |
