Phosphor-coated lamps

In fluorescent lamps, phosphors are coated on the inside of the lamp tube using a slurry containing the powder and a Hquid which is either poured down through the tube, up-flushed, or in some cases the tubes are filled and then drained. Because of concerns over having volatile organic solvents in the air, the hquid medium containing the powder is usually water with an added agent, a thickener, to increase the viscosity of the suspension, such as poly(methacryhc... 

In fact, most neon lamps are mercury lamps in which the inside of the tube is coated with a phosphor. To see if the lamp is truly neon-based, look at the bulb before it glows a real neon lamp needs no phosphor coating, so the glass is clear and without frosting. ... 

The Laboratory Data Control Fluoro Monitor (Fig.3.52) is a modular fluorescence detector similar in appearance to their UV detectors. With this detector, measurements may be made of the fluorescence of one stream or the differential fluorescence of two streams. The single-wavelength excitation source (a hot-cathode mercury lamp with a phosphor coating) emits a band of light with a maximum at 360 nm. The cell assembly is... 

Having available a certain number of LED sets might also be an alternative to having the above-mentioned sets of phosphor-coated lamps. Whilst the former set-up would be more expensive than the latter, it would be much more versatile, because in the case of LEDs a much wider choice of X is available (unfortunately, this is not as... 

A detailed description of the excimer set-up is given in reference [63a], The potassium salt of 12 g (31.7 mmol) A-phthaloylanthranilic acid amide 81 was irradiated in ca. 2000 mL of water/acetone (40 1) for 3h. The crude reaction mixture was extracted with ethyl acetate, the combined organic layers were dried over MgS04 and evaporated to give 5.5 g of the pyrrolobenzodiazepine 82 (52%, 4 6 tran cis-mixture). Alternatively, a Rayonet photochemical reactor equipped with phosphor coated 300 lOnm lamps can be used for reactions on a smaller scale. 

The emission characteristics of a particular lamp are dependent on tube current, mercury pressure, phosphor composition, phosphor coating procedure, tube composition, and the frequency of the ballast used. Since these lamps are produced for a very competitive commercial market, much of the production information is considered proprietary and not published. Changes can be made, sometimes without the knowledge of customers. 

A finely ground sample of compound 1 a (200 mg) was evenly spread on a 5 cm x 20 cm glass plate and exposed to the light from two 15 W phosphor-coated lamps (366 nm) at 10 cm distance. The powder was occasionally mixed. After 10 h, the powder was washed with a little chloroform, dissolving some unreacted starting material. The colorless residue (140 mg) was practically pure dimer 3 a, as shown by the spectrum. This could be recrystallized from nitro-methane. 

Photodegradation of six purified aromatic dyes All experiments were carried out in 10 mL cylindrical quartz cuvettes also placed in an RPR-200 Rayonet photochemical. Light sources were twelve 253.7 nm phosphor-coated low-pressure mercury lamps with a total power consumption of 400 watts. The light intensity at 1.5 inches from the lamps was about 21000 p watt/cm2 (Light intensity 2.4 x 10 5 Einstein L s 1) (Rabek J.K., 1982). The purified dyes were prepared at 50 mg/L, and were placed into the rotating merry-go-round photoreactor in which the cuvettes were exposed to same amount of UV light during the reaction. Samples were collected from each quartz cuvette at time 0, 15, 30, 60, 150, 240. 300 and 360 minutes, and then they were analysed by HPLC and/or UV-... 

The stock solution of disperse dye was prepared by dissolution of dye in a mixed 1 2 (v/v) acetone/H20 solution and the pH of the resulting solution was adjusted to 9. The UV irradiation of disperse dyes was carried out in a 50mL cylindrical quartz bottle. The dyebath was placed in a photo-reactor equipped with a UV lamp and the dye solution was stirred to maintain homogeneity. The light sources were ten 254 nm phosphor-coated low-pressure mercury lamps with a total output power of 500 watts. The light intensity at 5 cm distance fi om the lamps was about 2.25x10 photons/sec/cm. ... 

In addition to the low-pressure mercury lamp discussed above, there is the high-pressure mercury lamp (Rg. 6.3). The gas discharge is contained in a small envelope surrounded by a larger bulb. The phosphor coating is applied to the inside of the outer bulb, so that there is no contact with the discharge. 

When measm ing intensities for a phosphor-coated lamp, a correction factor is needed to obtain the true absolute reading. A coiTection factor can be calculated using the following relationship. 

Figure 9.4. The relative intensities of three different sources. A The emission intensity of the short-wavelength (254 nm) mercury arc. B The emission intensity of the phosphor-coated mercury arc, showing the intense emission band. C The intensity of the xenon-arc lamp.

Mercury Vapor Lamp- A high-intensity discharge lamp that uses mercury as the primary light-producing element. Includes clear, phosphor coated, and self-ballasted lamps. 

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