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
Famous quotes containing the word population:
“In our large cities, the population is godless, materialized,—no bond, no fellow-feeling, no enthusiasm. These are not men, but hungers, thirsts, fevers, and appetites walking. How is it people manage to live on,—so aimless as they are? After their peppercorn aims are gained, it seems as if the lime in their bones alone held them together, and not any worthy purpose.”
—Ralph Waldo Emerson (1803–1882)