Secondary emission in physics is a phenomenon where primary incident particles of sufficient energy, when hitting a surface or passing through some material, induce the emission of secondary particles. The primary particles are often charged particles like electrons or ions. If the secondary particles are electrons, the effect is termed secondary electron emission. In this case, the number of secondary electrons emitted per incident particle is called secondary emission yield. If the secondary particles are ions, the effect is termed secondary ion emission.
Famous quotes containing the words secondary and/or emission:
“Scientific reason, with its strict conscience, its lack of prejudice, and its determination to question every result again the moment it might lead to the least intellectual advantage, does in an area of secondary interest what we ought to be doing with the basic questions of life.”
—Robert Musil (1880–1942)
“Approximately 80% of our air pollution stems from hydrocarbons released by vegetation, so let’s not go overboard in setting and enforcing tough emission standards from man-made sources.”
—Ronald Reagan (b. 1911)