Mercury lamp, medium pressure

Parameter Low Pressure Mercury Lamp Medium Pressure Mercury Lamp High Pressure Mercury Lamp... 

The spectral output of the medium-pressure lamp can be altered by "doping," i.e., adding a small amount of metal halide to the fill material, with mercury. Commonly doped lamps are iron and gallium lamps. Medium-pressure lamps have long lifetimes (typically in excess of 3,000 h), although the intensity of the emitted light and the relative intensity of the spectral lines change with time. This affects their performance to the point that... 

UV lamp is the most crihcal element in the disinfection. The most widely used UV lamps can be classihedinto low-pressure low-intensity lamp, low-pressure high-intensity lamp, medium-pressure high-intensity lamp, high-pressure high-density lamp, and other types of lamps. The details of the typical lamps are listed in Table 3. The low-pressure mercury lamp works in an internal pressure range of 0.001-0.1 torr. Mercury is typically... 

The water is treated with UV radiation for primary disinfection, then chlorinated for secondary disinfection. An applied chlorine dosage of only about 1 mg/L is necessary. The entire water treatment system is housed in a 2.97 m (32 fU) building. The UV disinfection system consists of six irradiation chambers, two control cabinets with alarms, chart recorders, relays, hour-run meters, lamp and power on-lights, six thermostats, electrical door interlocks, mimic diagrams, and six UV intensity monitors measuring the total UV output. Each irradiation chamber contains one 2.5-kW mercury vapor, medium-pressure arc tube, generating UV radiation at 253.7 nm. 

Five basic lamp systems are available to produce UV radiation (1) medium-pressure mercury vapor lamps (2) electrode less lamps (3) pulsed xenon lamps (4) hybrid xenon/ mercury vapor lamps and (5) low-pressnre germicidal lamps. Medium-pressure mercury lamps that emit a wide range of wavelengths are by far the most important radiation sources for curing of coatings. 

Tile only instance of isolation of a stable benzo-l,2-dithiete is the yellow crystalline compound 187, which was obtained by photolysis of 188 in heptane at -20°C using a medium-pressure mercury lamp [75JCS(CC)756 77JCS(P1)515],... 

It was found out that when the bisfuranones 299 (R = H, Me, CMc3, TMS) were irradiated in a solution of acetone saturated with ethylene (medium pressure, 125 W, mercury lamp at —78°C), the biscyclobutane adducts 300, 301, and 302... 

Complexed arenediazonium salts are stabilized against photochemical degradation (Bartsch et al., 1977). This effect was studied in the former German Democratic Republic in the context of research and development work on diazo copying processes (Israel, 1982 Becker et al., 1984) as well as in China (Liu et al., 1989). The comparison of diazonium ion complexation by 18-crown-6 and dibenzo-18-crown-6 is most interesting. Becker at al. (1984) found mainly the products of heterolytic dediazoniation when 18-crown-6 was present in photolyses with a medium pressure mercury lamp, but products of homolysis appeared in the presence of dibenzo-18-crown-6. The dibenzo host complex exhibited a charge-transfer absorption on the bathochromic slope of the diazonio band. Results on the photo-CIDNP effect in the 15N NMR spectra of isotopically labeled diazonium salts complexed by dibenzo-18-crown-6 indicate that the primary step is a single electron transfer. 

The single-electron transfer from one excited component to the other component acceptor, as the critical step prior to cycloaddition of photo-induced Diels Alder reactions, has been demonstrated [43] for the reaction of anthracene with maleic anhydride and various maleimides carried out in chloroform under irradiation by a medium-pressure mercury lamp (500 W). The (singlet) excited anthracene ( AN ), generated by the actinic light, is quenched by dienophile... 

The apparatus is dried in an oven at 140° overnight and cooled under nitrogen or argon prior to the irradiation. A Vycor filter sleeve and a 450-watt medium-pressure mercury lamp are placed in the immersion well. The Vycor filter, the quartz immersion well (catlog No. 19434), the 450-watt mercury lamp (catalog No. 679A36), and the requisite transformer are all available from Hanovia Lamp Division, Canrad-Hanovia Inc., 100 Chestnut Street, Newark, New Jersey 07105. 

Since chlorinated PVC is totally transparent in the near-UV and visible range, it will not absorb at 488 nm, the emission line of the argon ion laser that we intended to use to perform the carbonization. Therefore C-PVC films were first exposed to the UV radiation of a medium pressure mercury lamp in order to produce the strongly absorbing polyenes. This irradiation was carried out at room temperature in the absence of oxygen, thus preventing the formation of undesirable oxidation products. 

Since our main objective was to remove all the chlorine and hydrogen atoms from the polymer chain, C-PVC films were further exposed to the UV radiation of the medium pressure mercury-lamp. This led to a dark brown material w.hich was found to be unable to carry an electrical current, even after extended irradiation time. Therefore we turned to a powerful laser source, a 15 W argon ion laser tuned to its continuous emission at 488.1 nm. At that wavelength, the degraded polymer film absorbs about 30 % of the incident laser photons. The sample was placed on a X-Y stage and exposed to the laser beam at scanning rates in the range of 1 to 50 cm s, in the presence of air. 

When this resin was exposed as a thin film to the UV radiation of a medium pressure mercury lamp (80 W aiH), the crosslinking polymerization was found to develop extensively within a fraction of a second (18). The kinetics of this ultra-fast reaction can be followed quantitatively by monitoring the decrease of the IR absorption at 810 an-1 of the acrylic double bond (CHCH twisting). Figure 8 shows a typical kinetic curve obtained for a 20 pm thick film coated onto a NaCl disk and exposed in the presence of air to the UV radiation at a fluence rate of 1.5 x 10 6 einstein s-1 cm 2. 

Acylimidazoles in the presence of benzophenone lead to oxetanes on irradiation with a medium-pressure mercury lamp [8]... 

The energy distribution for the commonly used 450-W Hanovia medium-pressure mercury lamp is given in Table 2.5. 

Burdick and Jackson). All solutions were photolyzed to less than 5% conversion in a standard 3 ml capacity, 1-cm path length quartz cell. Samples were irradiated with a 450-Watt medium pressure, Hanovla mercury lamp focused through an appropriate band-pass filter (280 nm or 254 nm) onto the 1-cm quartz cell with the requisite solution. Test solutions could be purged with either helium or oxygen using a needle valve assembly attached to the tapered quartz cell neck. The loss of carbamate due to photolysis and the amounts of known photoproducts were determined quantitatively by GC using eicosane as an internal standard. The columns were 6 stainless steel containing Carbowax 20M on chromosorb G. 

Watt medium pressure mercury lamp through a pyrex filter, b - Ha, Hx, He, H5, Hc and represent the integrated areas of... 

In all the solvents studied the species responsible for the color with TFA were extremely photosensitive and were bleached in a few seconds when irradiated with unfiltered light from a medium pressure mercury lamp. 

The photooxidation was carried out in a commercial weathero-meter (Q-UV, Q-panel Co., Cleveland, Ohio). This apparatus uses medium pressure mercury fluorescent UV lamps (Sunlamps F5-40, Westinghouse Electric Corp.) which emit UV light in the 273-378 nm range with a maximum intensity at 310 nm. 

Chemat and his coworkers [92] have proposed an innovative MW-UV combined reactor (Fig. 14.7) based on the construction of a commercially available MW reactor, the Synthewave 402 (Prolabo) [9[. It is a monomode microwave oven cavity operating at 2.45 GHz designed for both solvent and dry media reactions. A sample in the quartz reaction vessel could be magnetically stirred and its temperature was monitored by means of an IR pyrometer. The reaction systems were irradiated from an external source of UV radiation (a 240-W medium-pressure mercury lamp). Similar photochemical applications in a Synthewave reactor using either an external or internal UV source have been reported by Louerat and Loupy [93],... 

Surface water photolysis t, 2 = 6.27 h in aqueous solution when irradiated with a 500 W medium pressure mercury lamp (Chen et al. 1996). 

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