Fluorescent

Fluorescent refers to the emission of light by a substance that has absorbed light or other electromagnetic radiation. It is a form of luminescence. In most cases, the emitted light has a longer wavelength, and therefore lower energy, than the absorbed radiation. The most striking examples of fluorescence occur when the absorbed radiation is in the ultraviolet region of the spectrum, and thus invisible to the human eye, and the emitted light is in the visible region.

History

The term fluorescent was first coined by George Gabriel Stokes in 1852. He made the discovery while studying the mineral fluorite, which glows with a fluorescent light when illuminated with ultraviolet light.

Mechanism

Fluorescence occurs when an orbital electron of a molecule, atom, or nanostructure, relaxes to its ground state by emitting a photon from an excited singlet state. The specific frequencies of exciting and emitted light are dependent on the particular system.

Applications

Fluorescence has many practical applications, including mineralogy, gemology, chemical sensors (fluorescence spectroscopy), fluorescent labelling, dyes, and optical brighteners, and biological detectors. It is used in the medical field for diagnostic and therapeutic uses.

See Also

• Luminescence
• Phosphorescence
• Bioluminescence
• Chemiluminescence

References

Fluorescent Resources
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