Source mercury discharge

Sources of radiation are all of lower than ideal intensity. One of the most commonly used is a mercury discharge in a quartz envelope, most of the higher-wavenumber radiation coming from the quartz rather than from the discharge plasma. 

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. 

In aquatic environments where point sources of industrial contamination have been identified, the elimination of mercury discharges has usually improved environmental quality. Such improvement has been reported for Minamata Bay (Table 5.4) for sediments in Saguenay Fjord, Quebec,... 

Ultraviolet sources are chiefly mercury-discharge lamps in various forms. These lamps are fragile and quite inefficient. The design of reactors using these lamps is hampered by these considerations, and by the limited ultraviolet transmission, of common glasses and solvents. The transmission is further decreased by coatings of opaque materials which form... 

Interest in trace element emissions received impetus from published reports of widespread atmospheric dissemination of these substances (1), especially mercury (2, 3), as a consequence of fossil fuel use. More current information indicates that the original mercury discharge estimates were overstated, since they were based on nonrepresentative, ore-associated coal samples (4). Of the fossil fuels, coal is considered the major source of atmospheric pollution (5) and, compared with oil and... 

A case of Minamata disease was caused by methyl mercury discharged by a chemical factory in Minamata City, Japan. Inappropriate treatment and discharge of toxic chemical substances by Chisso Corperation continued from 1932 to 1968, which resulted in creating and torturing more than 14,000 victims with a neurological syndrome. The disease was officially discovered in 1956 but it took another 12 years to shut down the source of pollutants. 

Emission Spectrum. Several sources are suitable for exciting the emission spectrum of I2. In previous editions of this text, the use of a low-pressure mercury discharge lamp was described, in which the green Hg line at 546.074 nm causes a transition from... 

At one time, the progress in the field of Raman spectroscopy of polymers was heavily dependent upon laser technology. The advent of accessible laser sources made it possible to replace the mercury-discharge lamp as an excitation source. Other developments, such as photomultipliers, computerization, or, most recently, sensitive array detectors made a tremendous impact on applications of this method in polymer analysis. 

While some of the mid-IR sources emit light below 400 cm the intensity drops off. A more useful source for the far-IR region is the high pressure mercury discharge lamp. This lamp is constructed of a quartz bulb containing elemental Hg, a small amount of inert gas, and two electrodes. When current passes through the lamp, mercury is vaporized, excited. 

The LDPE foils were placed in the glass vessel in the atmosphere of saturated vapors of phosphoryl chloride. The sorption of the UV sensitizer onto the surface of the PO foils took 24 hours. The foils were then irradiated by UV radiation in an open quartz tube having a diameter of 50 mm. The UV light with a wavelength X = 366 nm was emitted by a 400 W mercury discharge lamp. The distance (d) of the UV tube from the surface of polymer varied between 50 and 200 mm. The relative intensity of UV radiation is inversely proportional to the square ratio of the UV source distances according to the relation ... 

FIG. 7. Spectral distribution of radiation sources in relative units deuterium ( - -). xenon arc (-mercury discharge lamps ( ) ... 

In the center spot of a high-current mercury discharge lamp with very high pressure, the number of photons per mode is about 10 at the center frequency of the strongest emission line at A = 253.6 mm. This shows that, even in this very bright light source, the induced emission only plays a minor role. 

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