Transmission electron microscopy
Transmission electron microscopy
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DOI：
10.31399/asm.hb.v12.a0001836
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
Anthony E. Woods;John W. Stirling
中科院分区：
文献类型：
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作者：
Anthony E. Woods;John W. Stirling
有人建议将选定区域的衍射合并到这篇文章或部分中。（讨论）透射电子显微镜（TEM）是一种成像技术，通过电子束聚焦在样品上，使放大版本出现在荧光屏或照相胶片上（见电子显微镜），或由CCD相机检测到。1938年，多伦多大学的Albert Prebus和James Hillier使用Max Knoll和Ernst Ruska提出的概念制造了第一台实用的透射电子显微镜。在过去，光学显微镜主要用于成像，因为它们相对容易使用。然而，可以成像的最大分辨率是由用于探测样品的光子的波长决定的。在显微镜技术的早期，任何小于所用波长的东西都无法被分辨，而如今，RESOLFT定律为光学显微镜使用这类概念设定了限制。可见光的波长为400-700纳米；比许多有趣的物体都大。紫外线可以使用，但很快就会遇到吸收的问题。即使是波长更短的，比如x射线，也表现出缺乏相互作用：无论是聚焦（没有任何相互作用强到足以充当透镜），还是实际与样品相互作用。像所有的物质一样，电子同时具有波动和粒子的特性（正如路易-维克多·德布罗意的理论），它们的波动特性意味着电子束在某些情况下可以表现得像一束辐射。波长取决于它们的能量，因此可以通过调整加速场来调节，并且可以比光的波长小得多，但由于它们的电荷，它们仍然可以与样品相互作用。电子产生的过程被称为热离子放电，其方式与阴极射线管中的阴极相同，或通过场发射；然后它们被电场加速，并被电场和磁场聚焦到样品上。电子可以聚焦在样品上，提供比光学显微镜更好的分辨率，并且具有更好的视觉深度。通过使用染色剂，可以在光学显微镜下增强样品的细节；与电子显微镜类似，铅或铀等重金属化合物可以…
(Redirected from Transmission electron microscope) It has been suggested that Selected area diffraction be merged into this article or section. (Discuss) Transmission electron microscopy (TEM) is an imaging technique whereby a beam of electrons is focused onto a specimen causing an enlarged version to appear on a fluorescent screen or layer of photographic film (see electron microscope), or to be detected by a CCD camera. The first practical transmission electron microscope was built by Albert Prebus and James Hillier at the University of Toronto in 1938 using concepts developed earlier by Max Knoll and Ernst Ruska. In the past, light microscopes have been used mostly for imaging due to their relative ease of use. However, the maximum resolution that one can image is determined by the wavelength of the photons that are being used to probe the sample. In the early days of microscopy nothing smaller than the wavelength being used could be resolved, whereas nowadays the law of RESOLFT sets the limit for optical microscopes employing such concepts (see microscope). Visible light has wavelengths of 400–700 nanometers; larger than many objects of interest. Ultraviolet could be used, but soon runs into problems of absorption. Even shorter wavelengths, such as X-rays, exhibit a lack of interaction: both in focusing (nothing interacts strongly enough to act as a lens) and actually interacting with the sample. Like all matter, electrons have both wave and particle properties (as theorized by Louis-Victor de Broglie), and their wave-like properties mean that a beam of electrons can in some circumstances be made to behave like a beam of radiation. The wavelength is dependent on their energy, and so can be tuned by adjustment of accelerating fields, and can be much smaller than that of light, yet they can still interact with the sample due to their electrical charge. Electrons are generated by a process known as thermionic discharge in the same manner as the cathode in a cathode ray tube, or by field emission; they are then accelerated by an electric field and focused by electrical and magnetic fields onto the sample. The electrons can be focused onto the sample providing a resolution far better than is possible with light microscopes, and with improved depth of vision. Details of a sample can be enhanced in light microscopy by the use of stains; similarly with electron microscopy, compounds of heavy metals such as lead or uranium can …