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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 ...
UVC or Ultraviolet Germicidal Irradiation is a function used in modern air conditioners which reduces airborne viruses, bacteria, and fungi, through the use of a built-in LED UV light that emits a gentle glow across the evaporator. As the cross-flow fan circulates the room air, any viruses are guided through the sterilization module’s ...
These two changes combine to allow the 253.7 nm ultraviolet light produced by the mercury arc to pass out of the lamp unmodified (whereas, in common fluorescent lamps, it causes the phosphor to fluoresce, producing visible light). Germicidal lamps still produce a small amount of visible light due to other mercury radiation bands.
These lamps emit ultraviolet light with two peaks in the UVC band at 253.7 nm and 185 nm due to the mercury within the lamp, as well as some visible light. From 85% to 90% of the UV produced by these lamps is at 253.7 nm, whereas only 5–10% is at 185 nm. [39] The fused quartz tube passes the 253.7 nm radiation but blocks the 185 nm wavelength.
Optical radiation is the part of the electromagnetic spectrum with wavelengths between 100 nm and 1 mm. [1] [2] This range includes visible light, infrared light, and part of the ultraviolet spectrum. [3] Optical radiation is non-ionizing, [4] and can be focused with lenses and manipulated by other optical elements.
where is the spectral radiance, the power emitted per unit emitting area, per steradian, per unit wavelength; is the speed of light; is the Boltzmann constant; and is the temperature in kelvins. For frequency ν {\displaystyle \nu } , the expression is instead
Excimer lamps are quasimonochromatic light sources operating over a wide range of wavelengths in the ultraviolet (UV) and vacuum ultraviolet (VUV) spectral regions. Operation of an excimer lamp is based on the formation of excited dimers (), which spontaneously transiting from the excited state to the ground state result in the emission of UV photons.
In addition to air filters, cleanrooms can also use ultraviolet light to disinfect the air. [14] UV devices can be fitted into ceiling light fixtures and irradiate air, killing potentially infectious particulates , including 99.99 percent of airborne microbial and fungal contaminants. [ 15 ]