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WonderMicroscopy technology

Electron microscopes use beams of electrons, focused by magnets instead of glass lenses, to show details far smaller than any light microscope can, down to viruses and even rows of atoms. Ernst Ruska and Max Knoll built the first one in Berlin in 1931.

Electron microscope

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A light microscope cannot separate details much smaller than about half the wavelength of light, roughly 200 nanometres. Electrons also behave as waves, and when accelerated their wavelength becomes many thousands of times shorter. Ruska and Knoll used magnetic coils to focus them in 1931, and by 1933 Ruska's instrument could show finer detail than any light microscope. Siemens sold the first commercial model in 1939. Transmission electron microscopes send electrons through very thin slices; scanning electron microscopes sweep a beam across a surface and build a three-dimensional-looking picture from the signals that come back. Samples must sit in a vacuum and be carefully prepared, but the images opened up the inner structure of cells, viruses and materials. Ruska shared the 1986 Nobel Prize in Physics.

Türkçe oku
Elektron mikroskopları, cam mercek yerine mıknatıslarla odaklanan elektron demetleri kullanır. Böylece hiçbir ışık mikroskobunun gösteremeyeceği kadar küçük ayrıntıları, virüsleri, hatta atom dizilerini görünür kılar. İlk örneğini Ernst Ruska ile Max Knoll 1931'de Berlin'de yaptı.

Işık mikroskobu, ışığın dalga boyunun yaklaşık yarısından, yani 200 nanometre kadarından küçük ayrıntıları birbirinden ayıramaz. Elektronlar da dalga gibi davranır ve hızlandırıldıklarında dalga boyları binlerce kat kısalır. Ruska ile Knoll 1931'de elektronları manyetik bobinlerle odakladı; Ruska'nın 1933'teki aygıtı en iyi ışık mikroskobundan daha ince ayrıntıları gösterebiliyordu. Siemens ilk ticari modeli 1939'da satışa çıkardı. Geçirimli elektron mikroskopları elektronları çok ince kesitlerin içinden geçirir; taramalı elektron mikroskopları ise yüzeyi bir demetle tarar ve geri dönen sinyallerden üç boyutlu görünen bir görüntü oluşturur. Örneklerin vakumda tutulması ve özenle hazırlanması gerekir; ama bu görüntüler hücrelerin, virüslerin ve malzemelerin iç yapısını gözler önüne serdi. Ruska 1986 Nobel Fizik Ödülü'nü paylaştı.

Sources and further reading

Background reading: Electron microscope
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