Phosphorescence | previous | next | feedback |
Definition: a luminescence which lasts for a relatively long time after excitation of a medium
Phosphorescence is a kind of photoluminescence (i.e., a kind of light emission of a medium) which lasts relatively long after excitation of the medium. The excitation energy is stored in metastable electronic states (often triplet states), exhibiting only forbidden transitions to lower states. The stored energy can be released only through relatively slow processes, which are often thermally activated.
Important phosphorescent materials are phosphorus, europium-doped strontium aluminate (Eu:SrAl2O4) and zinc sulfide (ZnS). They are used e.g. in safety products such as exit signs, which are visible even under conditions of power failure.
Fluorescent lamps also exhibit a low level of phosphorescence for some time after being switched off.
See also: luminescence, photoluminescence, metastable states
Category: physical foundations
Since October 2008, the Encyclopedia of Laser Physics and Technology is also available in the form of a two-volume book. Maybe you would enjoy reading it also in that form! The print version has a carefully designed layout and can be considered a must-have for any institute library, laser research group, or laser company.
You may order the print version via Wiley-VCH.
