Tungsten filament lamps

Almost all emission that we usually encounter, such as that from a sodium vapour or tungsten filament lamp, is of the spontaneous type. 

Kingery 1990) and sold very widely, but they had to capitulate to the tungsten filament lamp after 1911. They had an effective commercial life of only 12 years. 

AMD 1 Incandescent lamps - Safety specifications. Tungsten filament lamps for domestic and similar general lighting purposes (AMD 9115) dated January 1998. Superseded by BS EN 60432-1 2000, but remains cuiTcnt... 

Both fixed and variable wavelength uv/visible detectors are available. The variable types use a deuterium and/or a tungsten filament lamp as the radiation source and can operate between about 190-700 nm. They will have a number of absorbance ranges (ranges are given... 

A light source used frequently for ultraviolet absorption studies is the deuterium lamp. If an instrument is meant strictly for ultraviolet work, then the deuterium lamp is the only light source present and the instrument is called a UV spectrophotometer. Often, both a tungsten filament lamp and a deuterium lamp are present and are individually selectable. Also, instead of having two independently selectable... 

Is the intensity of light emitted by the various light sources used for visible and ultraviolet work the same at all emitted wavelengths How does intensity vary with wavelength for a tungsten filament lamp ... 

Halogen lamps are ordinary tungsten filament lamps in which the lamp bulb contains a small amount of a halogen (often bromine). At the high temperatures of the lamp, the halogens dissociate and exist as single atoms. 

The International Commission on Illumination (CIE) International Commission on Illumination (CIE) has defined a set of standard illuminants to be used for colorimetry (International Commission on Illumination 1996). Figure 3.21 shows the CIE illuminants A, C, Z>5o, Z>55, Z>65, and D15. Illuminant A represents the power spectrum of light from a black-body radiator at approximately 2856 K. If this type of light is required for experiments, a gas-filled tungsten filament lamp that operates at a temperature of 2856 K is to be used. Illuminant Z>65 represents a phase of daylight with a correlated color temperature of approximately 6500 K. The CIE recommends to use this illuminant wherever possible. 

A solution of the steroid (50 mg, 0.12 mmol) in cyclohexane (10 ml) containing DIB (40 mg, 0.12 mmol) and iodine (28 mg, 0.11 mmol) was irradiated with two 100 W tungsten-filament lamps for 50 min at 40°C. The reaction mixture was poured into water and extracted with ether the organic layer was washed with aqueous sodium thiosulphate and then water, dried, concentrated and the residue was purified by column chromatography on silica gel (hexane-ethyl acetate, 9 1) to give 6/ ,19-epoxy-5a-cholestan-3/I-yl acetate (45 mg, 90%) m.p. 114-115°C. 

A solution or suspension of the acid (1 mmol) in carbon tetrachloride (75 ml) containing DIB (0.55 mmol) and iodine (0.5 mmol) was irradiated with two 100 W tungsten-filament lamps for 45 min at reflux temperature. Another portion of DIB (0.55 mmol) was then added and irradiation was continued for 45 min at reflux. The reaction mixture was washed with dilute sodium thiosulphate and water, concentrated and chromatographed (silica gel column, 9 1 hexanes-ethyl acetate) to afford the alkyl iodide. Several steroidal acids with the carboxyl group attached at a 1° or 2° carbon atom gave the corresponding iodides in good yields. Acids with a 3° a-C instead of the iodide afforded alkenes similarly, alkenes were formed with a fivefold excess of DIB in the presence of cupric acetate. Aromatic acids also underwent iododecarboxylation, in moderate yields very effective was the otherwise difficult transformation of 1,8-naphthalenedicarboxylic acid to 1,8-diiodonaphthalene (80%) [68]. Cubyl and homocubyl iodides were also prepared in excellent yield [69]. 

Perhaps little attention has been devoted to a disturbing report by Frydman and Mazur (1970) concerning, in general, the reactivity of vinyl tosylates which possess at least one /3-hydrogen and, in particular, that of the isomeric 1,2-diphenylvinyl tosylates (134). These compounds, when heated at temperatures of at least 100° or irradiated with a tungsten filament lamp, are converted into the /8-ketosulphone 135 and the mechanism is a free-radical one as indicated in Scheme 13. 

Smithells (Trans. Chem. Soe., 1922, lai, 2236) suggests the possible formation of a thorium tungsten bronze in the tungsten filament lamp. 

Light source Tungsten filament lamp LEDs, xenon flashlamp LEDs Tungsten halogen lamp Xenon flash- lamp Mercury vapour lamp Tungsten halogen lamp... 

The common units of light intensity or power density of light emitted or received are as shown above. Care should be taken in comparing luminances. For example. Table 18.1 reveals that a tungsten filament lamp has about a tenth of the luminance of the sun, but the area of the sun s emitting surface is massively greater than that of a filament lamp, and therefore the luminous intensity of the sun is massively greater than the luminous intensity of the filament lamp. 

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