What is meant by secondary emission

Secondary emission

Secondary emission In physics is a term for the emission of secondary particles or radiation induced by primary particles or radiation when it hits surfaces or traverses materials. The triggers for the secondary emission are often electrons, ions or high-energy radiation (X-ray or gamma radiation). If the secondary particles are electrons, one speaks of secondary electron emission, if it is ions, one speaks of secondary ion emission.

The energy distribution and emission rate of the secondary electrons allow conclusions to be drawn about the surface properties and the material properties. This is used in secondary electron microscopy, which is the standard operating mode in the scanning electron microscope. The sample is bombarded with an electron beam and the secondary electrons that are released are detected.

A secondary electron multiplier uses the generation of secondary electrons to amplify very small currents and thus make them easier to detect. The best-known design of such a multiplier is the photomultiplier.

In a secondary ion mass spectrometer, the generation of secondary ions by primary ions is used for surface analysis.

Other meanings

The term secondary issue is also used in business, whereby it means the offer of listed shares that were not previously sold on the stock exchange, but only privately. In technology, secondary emissions are sometimes used to describe the course of undesired side reactions in chemical processes that lead to the release of pollutants.