Electron Microscopy | 电子显微镜

📚 Electron Microscopy | 电子显微镜

Electron microscopy is a technique that uses a beam of accelerated electrons instead of visible light to examine specimens. In A-level biology, it is the key method for studying cell ultrastructure because it can resolve details far smaller than the wavelength of light. This article explains how electron microscopes work, compares the main types, and outlines their advantages, limitations and applications.

电子显微镜是一种利用加速电子束代替可见光来观察样品的技术。在 A-level 生物中，它是研究细胞超微结构的关键方法，因为它能分辨远小于光波长的细节。本文将解释电子显微镜的工作原理，比较主要类型，并概述其优势、局限和应用。

1. Principle of Electron Microscopy | 电子显微镜原理

An electron microscope uses a heated or field-emission electron gun to release electrons, which are accelerated by high voltage through a vacuum column. Electromagnetic lenses focus the beam; changing the current through these lenses alters magnification and focus.

电子显微镜使用热发射或场发射电子枪释放电子，电子在高电压下加速穿过真空镜筒。电磁透镜聚焦电子束；改变通过这些透镜的电流可调节放大倍数和聚焦。

Because electrons are easily scattered by gas molecules, the specimen chamber and column must be kept under a high vacuum. This is one reason why living cells cannot be observed directly.

由于电子很容易被气体分子散射，样品室和镜筒必须保持高真空。这也是活细胞无法直接观察的原因之一。

2. Wavelength and Resolution | 波长与分辨率

Resolution depends

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