Ultraviolet radiation

== Description ==
The portion of the electromagnetic spectrum with wavelengths ranging from 100-400 nanometers (nm). Ultraviolet (UV) radiation occurs between the violet end of the visible spectrum and the x-ray region. UV is not visible to humans directly, but may initiate visible, fluorescent reactions in some compounds. It is present in sunlight and is also generated by almost all types of electrical light sources. UV radiation is subdivided as follows: 
* UV-A (315-400 nm) has the lowest energy and longest wavelengths. UV-A is produced by black lightbulbs and sunlight. Also called blacklight and soft UV, UV-A is used for fluorescent emission examinations where it is usually split into short wave (315-345 nm) and long wave (345-400 nm). Fluorescence can occur in many materials (paints, dyes, varnishes, glass, ceramics, gemstones, cast iron, pottery, paper, metal, prints, textiles, ivory, banknotes, etc.). UV-A presents a potential hazard for skin and eyes, especially when produced by high power sources.
* UV-B (280-325 nm) is in the middle range and can be produced by sunlamps (tanning booths) and sunlight. In addition to UV-A, these ranges of radiation are most readily absorbed by organic compounds resulting in deterioration of materials as well as sunburns, skin cancer, and cataracts in humans. UV-B, however, also induces the body to produce vitamin D which is essential for life.
* UV-C (100-280 nm) has the shortest wavelengths and highest energy UV. UV-C is produced by germicidal lamps and are used for irradiation and to generate ozone. 
The high energy of UV radiation can initiate chemical reactions, such as oxidation, in many organic materials resulting in discoloration, fading, embrittlement and/or cracking. Glass transmits little UV radiation below 315 nm, while quartz does not transmit most radiation below 200 nm. UV absorbing chemicals can be added to glass and plastic to prevent transmission of any ultraviolet light.
 
Ultraviolet was discovered by the German physicist Johann Wilhelm Ritter in 1801. Ultraviolet radiation is involved in examination or analysis techniques like ultraviolet fluorescence photography, ultraviolet visible spectroscopy (UV-vis).
== Synonyms and Related Terms ==
ultraviolet light; UV light; UV radiation; UV-A; UVA; UV-B; UVB; UV-C; UVC; actinic light; blacklight rayonnement ultraviolet, ultraviolet, UV (Fr.); colour
== Risks ==
* Long-term overexposure of ultraviolet radiation is hazardous to eyes and skin and may produced erythema, photokeratitis (snow blindness), and/or skin cancer. 
* Short-term exposure is sometime used for medical treatments of psoriasis, vitiligo and acne. 
* UV radiation can initiate oxidation reactions in organic materials.
== Resources and Citations ==
* Wikipedia: Blacklight Accessed Mar 2024.
* Van Nostrand's Scientific Encyclopedia, Douglas M. Considine (ed.), Van Nostrand Reinhold, New York, 1976
* Ralph Mayer, A Dictionary of Art Terms and Techniques, Harper and Row Publishers, New York, 1969 (also 1945 printing)
* Matt Roberts, Don Etherington, Bookbinding and the Conservation of Books: a Dictionary of Descriptive Terminology, U.S. Government Printing Office, Washington DC, 1982
* Random House, Webster's Encyclopedic Unabridged Dictionary of the English Language, Grammercy Book, New York, 1997
* Bob Angelo, Gigahertz-Optik, Inc: contributed information
* The American Heritage Dictionary or Encarta, via Microsoft Bookshelf 98, Microsoft Corp., 1998
* Book and Paper Group, Paper Conservation Catalog, AIC, 1984, 1989
* Theodore J. Reinhart, 'Glossary of Terms', Engineered Plastics, ASM International, 1988
* Art and Architecture Thesaurus Online, http://www.getty.edu/research/tools/vocabulary/aat/, J. Paul Getty Trust, Los Angeles, 2000
Category:Materials database