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population inversion

noun, Physics.
1.
a condition of matter in which more electrons are in a high energy state than in a lower energy state, as is required for the operation of a laser.
Origin
1960-1965
1960-65
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2014.
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Examples for population inversion
  • Align the nuclei, tickle them, detect the energy drain incoming or emission when the stimulated population inversion decays.
population inversion in Science
population inversion  
The condition of having enough excited or high-energy states distributed in a material that a chain-reaction of stimulated emission can occur. Lasers, for example, need a constant power source that maintains population inversion in order to generate radiation continuously, since each stimulated emission reduces the population of high-energy states. See also stimulated emission.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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Encyclopedia Article for population inversion

in physics, the redistribution of atomic energy levels that takes place in a system so that laser action can occur. Normally, a system of atoms is in temperature equilibrium and there are always more atoms in low energy states than in higher ones. Although absorption and emission of energy is a continuous process, the statistical distribution (population) of atoms in the various energy states is constant. When this distribution is disturbed by pumping energy into the system, a population inversion will take place in which more atoms will exist in the higher energy states than in the lower

Learn more about population inversion with a free trial on Britannica.com
Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.
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