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Electron tomography is an extension of traditional transmission electron microscopy and uses a transmission electron microscope to collect the data. In the process, a beam of electrons is passed through the sample at incremental degrees of rotation around the center of the target sample.
In contrast to other electron tomography techniques, samples are imaged under cryogenic conditions (< −150 °C). For cellular material, the structure is immobilized in non-crystalline, vitreous ice , allowing them to be imaged without dehydration or chemical fixation , which would otherwise disrupt or distort biological structures.
This technique is called electron tomography. One of the difficulties with high resolution transmission electron microscopy is that image formation relies on phase contrast. In phase-contrast imaging , contrast is not intuitively interpretable, as the image is influenced by aberrations of the imaging lenses in the microscope.
The E-T secondary electron detector can be used in the SEM's back-scattered electron mode by either turning off the Faraday cage or by applying a negative voltage to the Faraday cage. However, better back-scattered electron images come from dedicated BSE detectors rather than from using the E–T detector as a BSE detector.
Operating principle of a transmission electron microscope. Transmission electron microscopy (TEM) is a microscopy technique in which a beam of electrons is transmitted through a specimen to form an image. The specimen is most often an ultrathin section less than 100 nm thick or a suspension on a grid.
A scanning transmission electron microscope (STEM) is a type of transmission electron microscope (TEM). Pronunciation is [stɛm] or [ɛsti:i:ɛm]. Pronunciation is [stɛm] or [ɛsti:i:ɛm]. As with a conventional transmission electron microscope (CTEM), images are formed by electrons passing through a sufficiently thin specimen.
For electron microscopes, film typically consisted of a gelatin and silver halide emulsion layer on a plastic support base. [2] The silver halide would be converted to silver upon exposure to the electron beam, and the film could then be chemically developed to form an image, which could be digitized for analysis using a film scanner. [2]
In the field of transmission electron microscopy, phase-contrast imaging may be employed to image columns of individual atoms; a more common name is high-resolution transmission electron microscopy. It is the highest resolution imaging technique ever developed, and can allow for resolutions of less than one angstrom (less than 0.1 nanometres ...