Carbon arc

Thus, either the emitted light or the ions formed can be used to examine samples. For example, the mass spectrometric ionization technique of atmospheric-pressure chemical ionization (APCI) utilizes a corona discharge to enhance the number of ions formed. Carbon arc discharges have been used to generate ions of otherwise analytically intractable inorganic substances, with the ions being examined by mass spectrometry. 

Dichromated Resists. The first compositions widely used as photoresists combine a photosensitive dichromate salt (usually ammonium dichromate) with a water-soluble polymer of biologic origin such as gelatin, egg albumin (proteins), or gum arabic (a starch). Later, synthetic polymers such as poly(vinyl alcohol) also were used (11,12). Irradiation with uv light (X in the range of 360—380 nm using, for example, a carbon arc lamp) leads to photoinitiated oxidation of the polymer and reduction of dichromate to Ct(III). The photoinduced chemistry renders exposed areas insoluble in aqueous developing solutions. The photochemical mechanism of dichromate sensitization of PVA (summarized in Fig. 3) has been studied in detail (13). 

Hours to 50% retention of initial tensile strength under carbon arc exposure, kj /m to 50% retention of tensile strength Florida under glass exposure. 

Fig. 6. Comparison of xenon arc, sunshine carbon arc, and Miami average 45°S daylight, where (-) represents xenon with Type S high borate filters, 0.35...

W/m -nm at 340 nm ( ) represents sunshine carbon arc with Corex and (-) represents daylight. Courtesy of Adas Electric Devices Co. 

A.STM D1499, a. Recommended Practicefor OperatingEight- and Water-Exposure Apparatus Carbon Arc Type) for Exposure of Plastics, Vol. 8.01, ASTM, Philadelphia, Pa., 1992. 

Electric-Arc Furnace. The electric-arc furnace is by far the most popular electric steelmaking furnace. The carbon arc was discovered by Sir Humphry Davy in 1800, but it had no practical appHcation in steelmaking until Sir William Siemens of open-hearth fame constmcted, operated, and patented furnaces operating on both direct- and indirect-arc principles in 1878. At that early date, the avadabiHty of electric power was limited and very expensive. Furthermore, carbon electrodes of the quaHty to carry sufficient current for steel melting had not been developed (see Furnaces, electric). 

Molten zones are also formed by radiant heating (71). The light source may be focused carbon arcs, xenon lamps, sunlight, or lasers. Very high temperatures have been achieved with all of these. For example, sapphire has been float-zoned in this manner, at over 2000°C. 

Vibrations and simple excitations flames, lamps, carbon arc, limelight... 

Real or gray bodies deviate from these ideal blackbody values by the A-dependent emissivity, but the color sequence remains essentially the same. This mechanism explains the color of incandescent light sources such as flames in a candle, tungsten filament light bulb, flash bulb, carbon arc, limelight, lightning in part, and the incandescent part of pyrotechnics (qv). 

Common name UNS designation Oxyacet-ylen e Weldabihty Carbon arc Metal arc Bra2-abih ty Solder-abU ity... 

Whereas multi-wall carbon nanotubes require no catalyst for their growth, either by the laser vaporization or carbon arc methods, catalyst species are necessary for the growth of the single-wall nanotubes [156], while two different catalyst species seem to be needed to efficiently synthesize arrays of single wall carbon nanotubes by either the laser vaporization or arc methods. The detailed mechanisms responsible for the growth of carbon nanotubes are not yet well understood. Variations in the most probable diameter and the width of the diameter distribution is sensitively controlled by the composition of the catalyst, the growth temperature and other growth conditions. 

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