Toward ultimate light efficiency on the cheap

(Phys.org) —Researchers at the University of Michigan have taken a major stride toward perfectly efficient lighting that is also relatively inexpensive and simple to make. The same material can also reveal the presence ...

Phosphorescence

Phosphorescence is a specific type of photoluminescence related to fluorescence. Unlike fluorescence, a phosphorescent material does not immediately re-emit the radiation it absorbs. The slower time scales of the re-emission are associated with "forbidden" energy state transitions in quantum mechanics. As these transitions occur very slowly in certain materials, absorbed radiation may be re-emitted at a lower intensity for up to several hours after the original excitation.

Commonly seen examples of phosphorescent materials are the glow-in-the-dark toys, paint, and clock dials that glow for some time after being charged with a bright light such as in any normal reading or room light. Typically the glowing then slowly fades out within minutes (or up to a few hours) in a dark room.

The study of phosphorescent materials led to the discovery of radioactivity in 1896.

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