Phosphorescence or fluorescence?

Phosphorescence and fluorescence are processes of light emission at low temperatures. In both processes, energy is absorbed and re-emitted in the form of visible light.

Fluorescent substances, like those shown in the photo above, absorb ultraviolet light and emit visible light.
Phosphorescence and fluorescence are special cases of luminescence. Luminescence, in turn, is the process of emitting light at low temperatures, unlike the thermoluminescence process . In luminescence , atoms absorb part of the energy coming from some external source, re-emitting it in the form of visible light . Check out in this text what are the characteristics of phosphorescence and fluorescence.


Phosphorescence occurs when a substance is able to absorb light produced by some external source, re-emitting it in the form of visible light, even after the lighting has been stopped . Substances of this type continue to emit a faint glow for time intervals ranging from seconds to hours.

A common example of a phosphorescent body is those residential switches that can easily be found in the dark. See the figure below, it shows a phosphorescent compass:


Unlike phosphorescence, fluorescent substances emit light only while receiving energy from some external source , just like ultraviolet lamps. That way, when the energy source ceases , the fluorescence process is stopped immediately .

A good example of fluorescent objects are white lamps . These lamps contain an ionized gas inside that, when accelerated, produces ultraviolet light . On the inside of these lamps, there is a powder that contains phosphorus. This powder absorbs ultraviolet radiation and immediately re-emits it in the form of all wavelengths of visible light, producing an intense white glow that features all wavelengths of visible light (also called polychromatic light).

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