Mercury vapour discharge

Moore [355] used the solvent extraction procedure of Danielson et al. [119] to determine iron in frozen seawater. To a 200 ml aliquot of sample was added lml of a solution containing sodium diethyldithiocarbamate (1% w/v) and ammonium pyrrolidine dithiocarbamate (1 % w/v) at pH to 4. The solution was extracted three times with 5 ml volumes of 1,1,2 trichloro-1,2,2 trifluoroethane, and the organic phase evaporated to dryness in a silica vial and treated with 0.1 ml Ultrex hydrogen peroxide (30%) to initiate the decomposition of organic matter present. After an hour or more, 0.5 ml 0.1 M hydrochloric acid was added and the solution irradiated with a 1000 W Hanovia medium pressure mercury vapour discharge tube at a distance of 4 cm for 18 minutes. The iron in the concentrate was then compared with standards in 0.1 M hydrochloric acid using a Perkin-Elmer Model 403 Spectrophotometer fitted with a Perkin-Elmer graphite furnace (HGA 2200). 

A fluorescent lamp is a linear arc tube, internally coated with a fluorescent powder, containing a low-pressure mercury vapour discharge. 

Figure 1.4 The results from a photoelectric effect experiment using a calcium metal surface Irradiated by radiation of various lines given out by a mercury-vapour discharge lamp...

Anon. (1991) UV Mercury Vapour Discharge Lamps HOK 120, TQ, HPR, HPK, Philips Lighting. 

The usual sources of ultraviolet radiation are hydrogen or deuterium discharge lamps (the latter usually being preferred) or the mercury vapour lamp. All ultraviolet sources must be fitted with quartz or silica glass windows and none of the lamps named emits any significant amounts of radiation above 400 nm. 

In the same manner, temperatures exceeding the ignition temperatures (see Table 1.3 in Section 1.2.2) or the maximum surface temperatures according to the temperature class of the apparatus (see Table 4.1 in Chapter 4) are permissible inside of d. This covers windings and rotors in motors, especially for low temperature classes T4, T5 and T6 as well as the discharge tubes of high pressure sodium or mercury vapour lamps in case of a broken lamp bulb, or the ovens of gas chromatographs. 

There are numerous modifications which can be made to the basic reactor design. The initial dissociation of the silane gas can be by ultraviolet (UV) light illumination (photo-CVD), which either excites the silane directly, or by energy transfer from mercury vapour introduced into the chamber. Photo-CVD reactors eliminate the electric discharge and prevent the bombardment of the growing film by ions from the plasma, which may be a source of defects. A different way of reducing bombardment is to separate the plasma from the growing... 

New Hazardous Waste Regulations were introduced in July 2005 and under these regulations electric discharge lamps and tubes such as fluorescent, sodium, metal halide and mercury vapour are classified as hazardous waste. While each lamp only contains a very small amount of mercury, vast numbers are used and disposed of each year, resulting in a significant environmental threat. The environmentally responsible way to dispose of lamps and tubes is to recycle them and this process is now available through electrical wholesalers, as described in Chapter 1. 

Electric discharge lamps - electric current passing through certain gases produced an emission of light. Mercury vapour or mercury-halide lamps, tubular fluorescent, and sodium discharge lamps are examples. 

In order to separate singlet oxygen Oj from the mixture of other discharged oxygen species, the entering stream of oxygen is saturated with mercury vapour, which reacts effectively only with atomic oxygen ... 

The inner discharge tube contains the mercury vapour and a smaii amount of argon gas to assist starting. The main eiectrodes are positioned at either end of the tube and a starting eiectrode is positioned ciose to one main eiectrode. 

By increasing the lamp s internal operating pressures and temperatures, high-intensity light can be produced. High-intensity discharge lamps are classified as mercury-vapour, metal-halide, or high-... 

Until the advent of lasers the most intense monochromatic sources available were atomic emission sources from which an intense, discrete line in the visible or near-ultraviolet region was isolated by optical filtering if necessary. The most often used source of this kind was the mercury discharge lamp operating at the vapour pressure of mercury. Three of the most intense lines are at 253.7 nm (near-ultraviolet), 404.7 nm and 435.7 nm (both in the visible region). Although the line width is typically small the narrowest has a width of about 0.2 cm, which places a limit on the resolution which can be achieved. 

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