secondary electron

Written by

The Information Architects of Encyclopaedia Britannica

Last updated

July 13, 2026

Quick Summary

A secondary electron is an electron emitted from a material's surface when it's bombarded by high-speed electrons or other charged particles. This process, known as secondary emission, occurs when the bombarding particles transfer kinetic energy to electrons within the material, giving them enough energy to escape.123

Secondary emission is significant in technologies like photomultiplier tubes and image intensifiers, which amplify weak electric currents. The number of secondary electrons emitted per incident electron is called the secondary emission coefficient, which varies with the energy of the bombarding particles and the properties of the target material. This phenomenon is also utilized in techniques like secondary ion mass spectrometry (SIMS) for surface analysis.345

Summary created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

5 Britannica Sources

Ask Britannica AI about this topic

Britannica doesn't have a full article on this topic, so we've curated a list of our relevant coverage.

electron tube
Secondary emission
…the emitted electrons are designated secondary. The amount of secondary emission depends on the properties of the material and the energy and angle of incidence of the primary electrons. Material properties are characterized by the secondary-emission ratio, defined as the number of secondary electrons emitted per primary electron. Typically, the…
Read More
…the emitted electrons are designated secondary. The amount of secondary emission depends on the properties of the material and the energy and angle of incidence of the primary electrons. Material properties are characterized by the secondary-emission ratio, defined as the number of secondary electrons emitted per primary electron. Typically, the…
Read More