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SEM of a Snowflake

The Scanning Electron Microscope (SEM) produces images via electron imaging. The sample’s topography is determined by analyzing signals produced from electron displacement.

In order for conventional SEM imaging to work properly the specimen must be able to conduct an electric charge. For non-metallic samples this requirement is often reached by applying a thin coating of gold, platinum or other metallic substances to the sample in order to produce a clearer image. The snowflake on the right was analyzed after being sputter-coated with platinum at cryogenic temperatures.

Standard microscopes can magnify snowflakes around 30-500x, with the SEM one can view details at over 100,000x. A low temperature SEM was used to generate these images which maintained the integrity of the crystal while magnifying from 93x to 36,000x.

SEM is used to perform surface analysis to solve problems such as:

When SEM is combined with Energy Dispersive Spectroscopy (EDS), SEM-EDS can determine the elemental composition of the sample.