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Understanding the Role of Existing Technology in the Fight Against COVID-19
Published in Ram Shringar Raw, Vishal Jain, Sanjoy Das, Meenakshi Sharma, Pandemic Detection and Analysis Through Smart Computing Technologies, 2022
In order to develop the mechanism of disinfection using UV light, the technology involved in the process needs to be understood. The UV-C used in the UVGI is produced by a lamp which emits short-wavelength radiations. The conventional lamps are usually made of mercury vapors enclosed in a fused quartz tube. The mercury vapors are either at low or high pressure depending on the requirement. The low-pressure lamps are similar to fluorescent lamps, but do not contain fluorescent phosphorus. Moreover, the quartz tube is used instead of the glass because the latter absorbs the UV radiations. Whereas the low-pressure mercury lamps give off 253.7 nm radiations, a broader emission may be obtained by using high-pressure mercury lamps, which work on the principle of arc discharge lamps. Since mercury is toxic in nature, alternative technology such as excimer lamps and light-emitting diodes (LEDs) are being used. In an excimer lamp, diatomic molecules are used which are excited from the ground state to the excited state using electric discharge method. The excited electrons come back spontaneously to the ground state emitting photons in the UV region. A wide range of radiation lamps may be made using different excimers. The LED technology is also mercury-free and uses solid-state semiconductor materials such as aluminum gallium nitride (AlGaN). The semiconductor LEDs are tunable for specific needs by doping or chemical modification of the active material. The advantages of LED lamps lie in its compact size; however, much work is needed to optimize its efficiency, device lifetime, and cost as compared to conventional methods.
Introduction to Optical, Infrared, and Terahertz Frequency Bands
Published in Song Sun, Wei Tan, Su-Huai Wei, Emergent Micro- and Nanomaterials for Optical, Infrared, and Terahertz Applications, 2023
Song Sun, Wei Tan, Su-Huai Wei
Besides hot planets, various artificial UV sources are developed including lamps, light-emitting diodes (LED) and lasers [5]. There are several kinds of lamps that could emit UV radiations. The first type is called black light or Wood’s lamp, which produces long wave UV radiation based on either fluorescent or incandescent mechanism. Black light is commonly used in the situation where no visible light is needed, for instance, to trace fluorescence-tagged biochemical substance or to detect counterfeit money. The second type is the short-wave UV lamp, which typically emits short-wave UV-C light with peaks at 253.7 nm and 185 nm due to the mercury vapor filled within the lamp. These short-wave UV lamps are extensively utilized for disinfection purpose (also named germicidal lamps) in biomedical, food and water industries. The third type is the gas-discharge lamp, which could empower flexible UV radiation at various spectral lines depending on the gas types containing in the tube. The most commonly used gas-discharge lamps are neon lamp, deuterium arc lamp, xenon arc lamp, and mercury-xenon arc lamp, which cover the whole UV-A/UV-B/UV-C bands. The fourth type is the metal-halide lamp offering a high intensity white radiation via a mixture of gaseous mercury and metal halide (e.g., sodium iodide), since the metal ion could disassociate from the halide compound during the operation and produce additional emission power. Lastly, excimer lamp is a quasi-monochromatic UV source originated from the spontaneous emission of excimer molecules, which spans over a wide range of UV spectra depending on the molecule types [6].
Vacuum-UV of polyetheretherketone (PEEK) as a surface pre-treatment for structural adhesive bonding
Published in The Journal of Adhesion, 2020
Elisa Arikan, Jens Holtmannspötter, Timo Hofmann, Hans-Joachim Gudladt
After cleaning with different polar liquids (water, ethanol), the PEEK specimens were irradiated by VUV radiation at different UV doses. The VUV surface treatment was performed with a Xenon excimer lamp (XERADEX) from Osram (München, Germany). The outer glass bulb of excimer lamp is filled with xenon gas and emits photons with a wavelength of 172 nm, which already belongs to the vacuum-UV (VUV) range.[19] This VUV excimer lamp is installed in a mirror box with an output window of 7.5 cm × 13.5 cm size at one side made of quartz. The inside of the mirror box is flushed with nitrogen to minimize absorption of the radiation by air. For surface treatment, the samples are located under the mirror box under ambient air condition. The process gas is therefore air.