Editing Fluorescence (section)

=== Lighting ===
{{further|Fluorescent lamp|Blacklight}}
[[File:Art exhibition under black light.jpg|thumb|Fluorescent paint and plastic lit by UV-A lamps ([[blacklight]]). Paintings by Beo Beyond.]]

The common [[fluorescent lamp]] relies on fluorescence. Inside the [[glass]] tube is a partial vacuum and a small amount of [[mercury (element)|mercury]]. An electric discharge in the tube causes the mercury atoms to emit mostly ultraviolet light. The tube is lined with a coating of a fluorescent material, called the ''[[phosphor]]'', which absorbs ultraviolet light and re-emits visible light. Fluorescent [[lighting]] is more energy-efficient than [[incandescent]] lighting elements. However, the uneven [[spectrum]] of traditional fluorescent lamps may cause certain colors to appear different from when illuminated by incandescent light or [[daylight]]. The mercury vapor emission spectrum is dominated by a short-wave UV line at 254&nbsp;nm (which provides most of the energy to the phosphors), accompanied by visible light emission at 436&nbsp;nm (blue), 546&nbsp;nm (green) and 579&nbsp;nm (yellow-orange). These three lines can be observed superimposed on the white continuum using a hand spectroscope, for light emitted by the usual white fluorescent tubes. These same visible lines, accompanied by the emission lines of trivalent europium and trivalent terbium, and further accompanied by the emission continuum of divalent europium in the blue region, comprise the more discontinuous light emission of the modern trichromatic phosphor systems used in many [[compact fluorescent lamp]] and traditional lamps where better color rendition is a goal.<ref name="How Fluorescent Lamps Work">{{cite web|last=Harris|first=Tom|title=How Fluorescent Lamps Work|url=http://home.howstuffworks.com/fluorescent-lamp.htm|work=HowStuffWorks|publisher=Discovery Communications|access-date=27 June 2010|url-status=live|archive-url=https://web.archive.org/web/20100706040948/http://home.howstuffworks.com/fluorescent-lamp.htm|archive-date=6 July 2010|date=2001-12-07}}</ref>

Fluorescent lights were first available to the public at the [[1939 New York World's Fair]]. Improvements since then have largely been better phosphors, longer life, and more consistent internal discharge, and easier-to-use shapes (such as compact fluorescent lamps). Some [[High-intensity discharge lamp|high-intensity discharge (HID) lamps]] couple their even-greater electrical efficiency with phosphor enhancement for better color rendition.<ref>{{Cite book |last=Flesch |first=P. |url=https://www.worldcat.org/oclc/262693002 |title=Light and light sources: high-intensity discharge lamps |date=2006 |publisher=Springer-Verlag |isbn=978-3-540-32685-4 |location=Berlin |oclc=262693002}}</ref>

White [[light-emitting diode]]s (LEDs) became available in the mid-1990s as [[LED lamp]]s, in which blue light emitted from the [[semiconductor]] strikes phosphors deposited on the tiny chip. The combination of the blue light that continues through the phosphor and the green to red fluorescence from the phosphors produces a net emission of white light.<ref>{{Cite journal|last1=Chen|first1=Lei|last2=Lin|first2=Chun-Che|last3=Yeh|first3=Chiao-Wen|last4=Liu|first4=Ru-Shi|date=2010-03-22|title=Light Converting Inorganic Phosphors for White Light-Emitting Diodes|journal=Materials|volume=3|issue=3|pages=2172–2195|doi=10.3390/ma3032172|issn=1996-1944|pmc=5445896|bibcode=2010Mate....3.2172C|doi-access=free}}</ref>

[[Glow stick]]s sometimes utilize fluorescent materials to absorb light from the [[chemiluminescence|chemiluminescent]] reaction and emit light of a different color.<ref name="How Fluorescent Lamps Work"/>