Fluorescence

Fluorescence is a physical phenomenon that is often used in biological and chemical research. It is the emission of light by a substance that has absorbed light or other electromagnetic radiation. The emitted light usually has a longer wavelength, and therefore lower energy, than the absorbed radiation.

Overview

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 most striking examples of fluorescence occur when the absorbed radiation is in the ultraviolet range of the spectrum, and thus invisible to the human eye, and the emitted light is in the visible range.

Applications

Fluorescence has many practical applications, including mineralogy, gemology, chemical sensors (fluorescence spectroscopy), fluorescent labelling, dyes, and biological detectors. In biology, the fluorescence microscope is used to study the distribution of substances in biological specimens.

Fluorescence in nature

Many substances in nature can fluoresce. For example, the skin, blood, and certain types of plants and minerals can emit light when exposed to ultraviolet light.

See also

• Fluorescence microscope
• Fluorescence spectroscopy
• Fluorescent labelling
• Fluorescent dye

References

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