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The wide-scale deployment of radio-frequency technologies was a key factor in the expansion of wireless devices and systems. However, the portion of the electromagnetic spectrum used by wireless systems is limited in capacity, and licenses to use parts of the spectrum are expensive. With the rise in data-heavy wireless communications, the ...
In frequency (and thus energy), UV rays sit between the violet end of the visible spectrum and the X-ray range. The UV wavelength spectrum ranges from 399 nm to 10 nm and is divided into 3 sections: UVA, UVB, and UVC. UV is the lowest energy range energetic enough to ionize atoms, separating electrons from them, and thus causing chemical reactions.
The WHO-standard ultraviolet index is a widely publicized measurement of total strength of UV wavelengths that cause sunburn on human skin, by weighting UV exposure for action spectrum effects at a given time and location. This standard shows that most sunburn happens due to UV at wavelengths near the boundary of the UVA and UVB bands.
Because UVC can be deadly, a special dichroic filter glass (usually purple) is required that will filter out the UVC and UVB. The goal with high-pressure tanning bulbs is to produce a high amount of UVA only. Unfiltered light from a high-pressure lamp is rich in UVC used in germicidal lamps, for water purification, but it damages human skin.
UV-B lamps are lamps that emit a spectrum of ultraviolet light with wavelengths ranging from 290–320 nanometers. This spectrum is also commonly called the biological spectrum due to the human body's sensitivity to light of such a wavelength. [1] UV-B light does not tan the skin very much, compared to the UV-A lamps that are used in tanning beds.
Since UVC extends to 100 nm, there is some overlap in the terms. The main uses of extreme ultraviolet radiation are photoelectron spectroscopy, solar imaging, and lithography. In air, EUV is the most highly absorbed component of the electromagnetic spectrum, requiring high vacuum for transmission.
Parameters of interest, besides the wavelength of measurement, are absorbance (A) or transmittance (%T) or reflectance (%R), and its change with time. [4] [5] A UV-Vis spectrophotometer is an analytical instrument that measures the amount of ultraviolet (UV) and visible light that is absorbed by a sample. It is a widely used technique in ...
There are four UVB types of lamps: Fluorescnt Broad-Band UVB that emit 280-330 nanometer, Fluorescent Narrow-Band that emit 312 nanometer, Excimer that emit 308 nanometer and LED that emit 290-300 nanometer. PUVA means UVA + psoralen. It consists of irradiation of the skin with the UVA ultraviolet light, from a fluorescent bulb or LED lamps.