What is Fluorescence?
[[Image:FluorescentCells.jpg|thumb|right|[[Endothelium|Endothelial cells]] under the microscope with three separate channels marking specific cellular components]] '''Fluorescence''' is the light given off by certain substances when it absorbs light or other [[electromagnetic radiation]]. First the substance absorbs the energy, then it emits light. When the light source is removed, the fluorescence stops occurring. It is a form of [[luminescence]]. In most cases, the light given off has a longer wavelength and lower energy than the absorbed light.<ref>''Principles of instrumental analysis'' F.James Holler, Douglas A. Skoog & Stanley R. Crouch 2006</ref> One of the most surprising types of fluorescence is when a substance absorbs [[ultraviolet light]] that cannot be seen by the human eye, but gives off visible light. Fluorescence is used in many fields such as [[mineralogy]], [[gemology]], chemical sensors ([[fluorescence spectroscopy]]), [[dye]]s, biological detectors, and [[fluorescent lamp|fluorescent light]]s. Fluorescence in the life sciences is a way of tracking biological molecules. A [[protein]] or other component can have a fluorescent [[dye]] attached to it, which allows a scientist to visually find the specific protein with a microscope.<ref>{{cite book|author=Joseph R. Lakowicz|title=Principles of fluorescence spectroscopy|url=https://books.google.com/books?id=-PSybuLNxcAC|accessdate=16 April 2011|year=2006|publisher=Springer|isbn=978-0-387-31278-1|page=xxvi}}</ref> == References == {{reflist}} [[Category:Light sources]]