Spontaneous emission is the process by which a light source such as an atom, molecule, nanocrystal or nucleus in an excited state undergoes a transition to a state with a lower energy, e.g., the ground state and emits a photon. Spontaneous emission of light or luminescence is a fundamental process that plays an essential role in many phenomena in nature and forms the basis of many applications, such as fluorescent tubes, older television screens (cathode ray tubes), plasma display panels, lasers (for startup - normal continuous operation works by stimulated emission instead) and light emitting diodes.
Read more about Spontaneous Emission: Introduction, Theory, Rate of Spontaneous Emission, Radiative and Nonradiative Decay: The Quantum Efficiency
Famous quotes containing the words spontaneous and/or emission:
“What is saved in the cinema when it achieves art is a spontaneous continuity with all mankind. It is not an art of the princes or the bourgeoisie. It is popular and vagrant. In the sky of the cinema people learn what they might have been and discover what belongs to them apart from their single lives.”
—John Berger (b. 1926)
“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)