Population Inversion

In physics, specifically statistical mechanics, a population inversion occurs when a system (such as a group of atoms or molecules) exists in a state with more members in an excited state than in lower energy states. The concept is of fundamental importance in laser science because the production of a population inversion is a necessary step in the workings of a standard laser.

Read more about Population Inversion:  Boltzmann Distributions and Thermal Equilibrium, The Interaction of Light With Matter, Selection Rules, Creating A Population Inversion, Other Methods of Creating A Population Inversion

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