Forskel mellem versioner af "Ultraviolet lys"

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=== Kemi ===
UV-stråling kan udløse kemiske processer. Typisk skal der tilføres en vis mængde energi før en kemisk elementarproces kan forløbe. Det viser sig at fotonenergien i UV-lys ofte er passende til at bryde en [[kemisk binding]] og danne [[radikalRadikal (kemi)|radikaler]]er, sammenlign f.eks. med [[bindingsenergi]]erne af C-H (410 kJ/mol), C-C (347-356 kJ/mol) og O-H (460 kJ/mol). Til sammenligning skal anføres at fotonenergien af synligt lys ligger mellem 1,8 og 3,1 eV, en relativt lille energi, men nok til at excitere et enkelt molekyle i øjets fotoreceptorer.
 
UV nedbryder langsomt mange typer af [[pigment]]er. Derfor opsættes et gult (UV-absorberende) folie i udstillingsruden i visse [[forretning]]er. Omvendt udnyttede man før fremkomsten af kemiske blegemidler i stor stil UV-strålingens blegende effekt ved fremstilling af hvide tekstiler.
=== Biologi ===
 
[[Menneske]]r kan per definition ikke se UV, men mange dyr, bl.a. [[bi]]er, [[rejeÆgte rejer|rejer]]r og [[krabbe]]r samt visse fisk og fugle, kan<ref>[http://www.halibut.net/What-Fish-See.htm Ultraviolet Light and Its Role in Predation in Fish. How Fool-a-Fish Was Discovered. By Milan Jeckle M. D.] Citat: "...So in summary, I was reading quality scientific research articles that were reporting that ultraviolet [UVA] traveled through [klart] water at least 700 feet [ca. 230 meter] and maybe as much as 2,500 feet [ca. 800 meter] before it was absorbed, unlike visible light which is completely absorbed in the first 40 feet [ca. 12 meter]...The result was the scientific recognition that bony fish and birds have a Rodopsin protein in their retinas which reacts to the ultraviolet wavelengths around 360 nm, a wavelength totally invisible to humans. We also discovered that insects, shrimp and crabs have similar keen ultraviolet vision..."</ref>. Deres øjnes UV-følsomhed topper typisk omkring 360 nm, dvs. i UVA-området. Solstrålingens UVA kan trænge flere hundrede meter ned i klart vand, hvorimod den røde ende af synligt lys er helt absorberet i ca. 12 meters dybde. På større dybder orienterer visse vandlevende dyr sig derfor vha. UVA. Blandt pattedyrene kan visse nektardrikkende [[flagermus]] se UVA, hvilket sætter dem i stand til at finde [[blomst]]er om natten<ref>[http://www.sciencedaily.com/releases/2003/10/031017073642.htm October 17, 2003, ScienceDaily: Bats Scan The Rainforest With UV-Eyes] Citat: "...[[Flagermus|Bats]] from Central and South American that live on the nectar from flowers can see ultraviolet light...Flower visiting bats seem to need UV-vision, because the [[Blomst|flowers]] they visit in the [[regnskov|rainforest]] are characterised by a strong reflection of UV-spectrum light at night. It remains open whether the unusually high UV-sensitivity found in these bats involves a further photo-mechanism that is as yet unknown for mammals..."</ref>.
 
=== Fysiologi ===
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