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The Epic Interactive Encyclopedia 1998
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Epic Interactive Encyclopedia, The - 1998 Edition (1998)(Epic Marketing).iso
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L
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Luminescence
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1992-09-03
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Emission of light from a body when its atoms
are excited to incandescence by means other
than raising its temperature. Short-lived
luminescence is called fluorescence;
longer-lived luminescence is called
phosporescence. When exposed to an external
source of energy, the outer electrons in
atoms of a luminescent substance absorb
energy and `jump' to a higher energy level.
When these electrons `jump' back to their
former level they emit their excess energy as
light. Many different exciting mechanisms are
possible: visible light or some other
electromagnetic radiation (ultraviolet rays
or X-rays), electron bombardment, chemical
reactions, friction, and radioactivity.
Certain living organisms produce
bioluminescence.