Mercury vapour lamp

Instruments for the measurement of fluorescence are known as fluorimeters or spectrofluorimeters. The essential parts of a simple fluorimeter are shown in Fig. 18.1. The light from a mercury-vapour lamp (or other source of ultraviolet light) is passed through a condensing lens, a primary filter (to permit the light band required for excitation to pass), a sample container, a secondary filter (selected to absorb the primary radiant energy but transmit the fluorescent... 

Lemington H.26X., made by the General Electric Co., is a very hard borosilicate glass of high softening temperature. Tte Mg point is 780°C. It is used in high pressure mercury vapour lamps. The linear expansion coefficient is 4-6 x 10 from 20 to 580°C. Sodium and potassiiun are absent and alumina is present in quantity in this glass. 

Frequently colourless substances can also be separated and purified by this procedure provided that the chromatogram, prepared in a tube of special glass or quartz, can be divided up in the light of a mercury vapour lamp, in accordance with the fluorescence induced. For example, carotene has thus been separated into three components (R. Kuhn, P. Karrer). 

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. 

The functionalization of H—Si(l 11) surfaces has been extended to the reaction with aldehydes. Indeed, H—Si(lll) reacts thermally (16 h at 85 °C) with decanal to form the corresponding Si—OCH2R monolayer that has been characterized by ATR-FTIR, XPS and atomic force microscopy (AFM) [63]. The reaction is thought to proceed either by a radical chain mechanism via adventitious radical initiation or by nucleophilic addition/hydride transfer. On the other hand, the reaction of H—Si(lll) with octadecanal activated by irradiation with a 150W mercury vapour lamp (21 h at 20-50 °C) afforded a R... 

Diverse instruments employing the principle of this experiment are used to measure mercury, a toxic and volatile element, present in many work areas. A device has been designed as a colorimeter dedicated for this single element. The source is a mercury vapour lamp and the cell is a transparent tube filled with the atmosphere to be monitored. If mercury vapours are present in the optical path, absorption of radiation emitted by the lamp will occur and this will lead to a decrease in the transmitted light intensity measured by the instrument. 

When illuminated by an incandescent gas lamp, tellurium vapour exhibits an intense bluish-green fluorescence. Under the light of a mercury vapour lamp the fluorescence is much less intense. The fluorescence spectrum consists of regularly spaced bands in the visible region.12... 

Method II.—10 gms. of p-nitrotoluene and a crystal of iodine dissolved in 100 c.cs. of carbon tetrachloride are placed in a silica flask provided with a reflux condenser. The solution is covered with water (about 50 c.cs.) and heated to gentle boiling, while situated about 15 cms. from a mercury vapour lamp (Fig. 46). A solution of 15 gms. bromine in 50 c.cs. carbon tetrachloride is then run in drop by drop from a dropping funnel at the top of the condenser. When all the bromine is in, boiling is continued until the solution becomes almost colourless. The contents of the flask are cooled, transferred to a separating funnel, and the lower carbon tetrachloride layer run into a distilling flask. Carbon tetrachloride is distilled off over a water bath, and the residue of p-nitrobenzyl bromide recrystallised from alcohol or petroleum ether. 

The Apparatus and General Methods section has been increased by the addition of an outline of the mercury vapour lamp and its uses in polari-metry and in catalytic reactions. A laboratory-scale apparatus, devised by us, for the distillation of solids is included. The section on the use of the library has been extended, and attention has been drawn to the changes which have taken place in the German reference literature. 

M. Berthelot 5 said that nitrogen peroxide is stable as such towards 500°, but this does not agree with the observation of A. Richardson, C. W. Hasenbach, and W. Ramsay and J. T. Cundall—vide supra. R. G. W. Norrish found that there is a slow increase in the press, of nitrogen peroxide illuminated by means of a mercury vapour lamp. The press, becomes normal in the dark the change is rapid at first, and afterwards slow. The suppression of the effect by the addition of excess of nitric oxide or oxygen, coupled with the fact that nitric oxide is the more effective agent, points to the establishment of a photochemical equilibrium, 2N02 2N0-t-02. 

Surface functionalisation of PE with succinic anhydride followed by derivatisation via ring opening reaction yielded surfaces with different functional groups [128]. The PE films were photochemically grafted with maleic anhydride in vapour phase in a reaction involving benzophenone and acetone at 60 °C for 5 h under UV irradiation with a 400 W mercury vapour lamp. The chemical transformation of PE film bearing succinic anhydride group is schematically presented in Scheme 8. 

Hanau Q 81 high-pressure mercury - vapour lamps fitted into Pyrex tubes were used as the radiation source for these acetone-initiated reactions. 

The last two methods are not generally applicable to the small laboratory except insofar as low pressure mercury vapour lamps emitting light of 254 nm may be used to sterilise the air in aseptic rooms and cabinets (see 9.4.1). 

Under the influence of ultraviolet light from a quartz mercury vapour lamp, however, ozone is capable of oxidising dry hydrogen, the following reactions taking place — ... 

Ultra-violet light, such as that emitted by a mercury-vapour lamp, exerts a powerful germicidal action on water and ice. In a series of experiments earned out at Marseilles it was observed that a lamp working with 3 amperes at 220 volts destroyed pathogenic organisms in water within a radius of 2 inches in two seconds.2 In order to ensure complete sterilisation m a stream of water, the latter is made to flow, by... 

The compounds to be separated from one another in chromatography need not always be coloured. Colourless substances can also be separated by this technique. Advantage, in some cases, is taken of the fact that certain colourless compounds show a bright fluorescence when exposed to ultraviolet light. The position of such a substance in the column can thus be followed with the help of a mercury vapour lamp. 

Luminaire for high pressure mercury vapour lamp, flameproof enclosure, terminal box in increased safety, containing the series reactor protected by powder filling, for chemical plants ... 

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. 

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