Lamps mercury-free

Fluorescent lamps. No viable replacement has yet been discovered for mercury in general-purpose fluorescent lamps. Mercury-free xenon-based fluorescent discharges are available in a flat-panel format, suitable for back lighting of liquid crystal displays, but the efficiency is approximately 30% of a normal mercury-based fluorescent lamp therefore, this technology is enviromnentally counterproductive for general lighting applications. 

The mercury-free fluorescent lamps and plasma display panels require alternative luminescent materials for efficient conversion of ultraviolet radiation to visible light. The quantum cutting (two photon luminescence or photon-cascade emission) was demonstrated in famous "Eu -Gd " pair" containing system employing the concept of down-conversion, which means that two visible photons are emitted after... 

If only this were true. There are long- and short-arc lamps and high, medium, and low pressure, and mercury-free and mercury-doped lamps in use (Fig. 9). 

I 1.6.14. Mercury-Containing and Mercury-Free Plasma Lamps... 

Ochiai T, Niitsu Y, Kobayashi G, Kurano M, Serizawa I, Horio K, Nakata K, Murakami T, Morito Y, Fujishima A (2011) Compact and effective photocatalytic air-puriAcation unit by using of mercury-free excimer lamps with Ti02 coated titanium mesh Alter. Catal Sci Technol 1 1328-1330... 

Bom, M., Strosser, M., Giese, H., Niemann, U., Peitz, W., Baeva, M., Meier, S., Reiter, D., Schubert, H., Weiss, M., Bauer, T., Neiger, M., Strobel, H., Hilpert K., Lohken, A., Markus, T., 2004. Mercury-free automotive discharge lamps. Institute of Physics Conference Series (182), 179-180. 

Chlorine free radicals used for the substitutioa reactioa are obtaiaed by either thermal, photochemical, or chemical means. The thermal method requites temperatures of at least 250°C to iaitiate decomposition of the diatomic chlorine molecules iato chlorine radicals. The large reaction exotherm demands close temperature control by cooling or dilution, although adiabatic reactors with an appropriate diluent are commonly used ia iadustrial processes. Thermal chlorination is iaexpeasive and less sensitive to inhibition than the photochemical process. Mercury arc lamps are the usual source of ultraviolet light for photochemical processes furnishing wavelengths from 300—500 nm. 

In the case of photoinitiated polymerization, an oxygen-free aqueous solution of acrylamide with a concentration of about 50% mixed with a photosensibilizer and other required additives is passed through a column-type apparatus with exterior water-cooling. A thin layer of the solution is exposed to a mercury lamp, acquires the consistency of a plastic film, which then can be passed through a second exposure zone, and is crushed and dried. Acrylamide polymers produced by this method are easily soluble and have a low residual monomer content. 

Previously, the same author [52] reported that compounds containing the tricoordinated sulfur cation, such as the triphenylsulfonium salt, worked as effective initiators in the free radical polymerization of MMA and styrene [52]. Because of the structural similarity of sulfonium salt and ylide, diphenyloxosulfonium bis-(me-thoxycarbonyl) methylide (POSY) (Scheme 28), which contains a tetracoordinated sulfur cation, was used as a photoinitiator by Kondo et al. [63] for the polymerization of MMA and styrene. The photopolymerization was carried out with a high-pressure mercury lamp the orders of reaction with respect to [POSY] and [MMA] were 0.5 and 1.0, respectively, as expected for radical polymerization. 

ESR spectra were recorded on a JEOL JES-RE2X spectrometer. About 250 mg of ruthenium-free titanate samples was subjected to heat treatment either in vacuum at 573 K or in a hydrogen atmosphere at 973 K. For measurements of ESR spectra, 30 Torr of O2 or N2O was introduced at room temperature and then cooled to 77 K without evacuation. The spectra were obtained in the dark and under UV irradiation with a 500 W low pressure mercury lamp. 

A typical source (see Figure 6-2) consists of an ultraviolet mercury lamp that irradiates a quartz tube through which clean air flows at 5-10 liters/min. A small amount of the oxygen in air is converted to ozone by photolysis. It is important that the incoming air be free of moisture, nitrogen oxides, sulfur oxides, hydrocarbons, and particles, to... 

Photolytic. Photolysis of acetone in air yields carbon monoxide and free radicals, but in isopropanol, pinacol is formed (Calvert and Pitts, 1966). Photolysis of acetone vapor with nitrogen dioxide via a mercury lamp gave peroxyacetyl nitrate as the major product with smaller quantities of methyl nitrate (Warneck and Zerbach, 1992). 

Photolytic. Plimmer and Hummer (1969) studied the irradiation of chloramben in water (2-4 mg/L) under a 450-W mercury vapor lamp (7, >2,800 A) for 2-20 h. Chloride ion was released and a complex mixture of colored products was observed. It was postulated that amino free radicals reacted with each other via polymerization and oxidation processes. The experiment was repeated except the solution contained sodium bisulfite as an inhibitor under a nitrogen atmosphere. Oxidation did not occur and loss of the 2-chloro substituent gave 3-amino-5-chlorobenzoic acid (Plimmer and Hummer, 1969). 

Esters of 2-(2-azidophenyl)ethyl alcohol are photolyzed under a high-pressure mercury lamp to a reactive nitrene intermediate which, following insertion into the alkyl side-chain, undergoes elimination to give the free carboxylic acid (up to 32%) and producing indole. The photochemical release was somewhat improved (65-80%) when 5-azido-4-(hydroxy-methyl)-l-methoxy naphthalene was used (see Scheme 27). 

Resins H11-H13 were UV-cured using a free radical photoinitiator (Iigacure 184 , 1-benzoylcyclohexanol) in a Mini-Cure equipped with medium-pressure mercury lamps (80 W/cm). The samples were postbaked at 100 °C for 20 minutes to obtain a similar thermal history for all samples. 

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