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Extremely hot stars (such as O- and B-type) emit proportionally more UV radiation than the Sun. Sunlight in space at the top of Earth's atmosphere (see solar constant) is composed of about 50% infrared light, 40% visible light, and 10% ultraviolet light, for a total intensity of about 1400 W/m 2 in vacuum.
Ultraviolet light therapy or ultraviolet phototherapy is a treatment for psoriasis, atopic skin disorder, vitiligo and other skin diseases. There are two main treatments: UVB that is the most common, and PUVA.
A low-pressure mercury-vapor discharge tube floods the inside of a biosafety cabinet with shortwave UV light when not in use, killing microbes on irradiated surfaces. Ultraviolet germicidal irradiation (UVGI) is a disinfection technique employing ultraviolet (UV) light, particularly UV-C (180–280 nm), to kill or inactivate microorganisms ...
Deuterium is used rather than normal hydrogen because of its greater intensity of UV emission in the molecular band. A deuterium lamp uses a tungsten filament and anode placed on opposite sides of a nickel box structure designed to produce the best output spectrum. Unlike an incandescent bulb, the filament is not the source of light in ...
c is the speed of light, λ is the wavelength of light. By applying this new energy to the partition function in statistical mechanics , Planck's assumptions led to the correct form of the spectral distribution functions: B λ ( λ , T ) = 2 h c 2 λ 5 1 exp ( h c λ k B T ) − 1 {\displaystyle B_{\lambda }(\lambda ,T)={\frac {2hc^{2 ...
Low power consumption of semiconductors introduce UV disinfection systems that utilized small solar cells in remote or Third World applications. [2] By 2019, LEDs made up 41.4% of UV light sales, up from 19.2% in 2014 [3] The UV-C LED global market is expected to rise from $223m in 2017 to US$991m in 2023. [4]
Photochemical immersion well reactor (50 mL) with a mercury-vapor lamp.. Photochemistry is the branch of chemistry concerned with the chemical effects of light. Generally, this term is used to describe a chemical reaction caused by absorption of ultraviolet (wavelength from 100 to 400 nm), visible (400–750 nm), or infrared radiation (750–2500 nm).
As can be seen in Figure 1, these detectors have a light source, a dispersion element that is a diffraction grating or prism, a flow cell, to where the sample arrives directly from the chromatographic column, an optical bench of lenses and mirrors, and a diode that receives the light coming from the optical system and translates it into a ...