EQUINOX GRAPHICS / SCIENCE PHOTO LIBRARY EQUINOX GRAPHICS / SCIENCE PHOTO LIBRARY
Animation showing the spontaneous emission of a photon. Initially the atom has electrons (blue) in the ground (lowest energy) state. A photon (yellow) from the surrounding electromagnetic field raises one to a higher energy level, further away from the nucleus (red). This can then fall back to the ground state, releasing a photon in a random direction, with properties of phase and polarisation unrelated to those of the photon that excited the atom. This is in contrast to stimulated emission, where emitted photons are all in phase and the same polarity. See K002 8520 for an animation of stimulated emission.
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