What is one requirement for samples observed with a Scanning Electron Microscope (SEM)?

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For samples observed with a Scanning Electron Microscope (SEM), it is essential that they are coated with a thin layer of metal. This requirement arises because SEM relies on the interaction of electrons with the surface of the sample to generate images. Non-conductive samples, such as biological tissues or certain plastics, can accumulate charge when exposed to the electron beam. This charging effect can distort the imaging process and lead to poor-quality images.

Coating the sample with a conductive metal—such as gold, platinum, or carbon—provides a path for the electrons to flow away, which minimizes charging effects and enhances image quality. The metal coating allows for the electrons to scatter off the surface effectively, creating detailed topographical images of the sample.

In contrast, samples that are in liquid form would not be suitable for SEM, as the microscope operates under vacuum conditions, which would cause liquids to evaporate. Additionally, there is no requirement for the samples to be organic or alive, as many inorganic materials can also be analyzed using SEM without any issues.

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