Tungsten filament atomizer

Williams, M. and Plepmeler, . H. "Commercial Tungsten Filament Atomizer for Analytical Atomic Spectrometry". 

Fig. 85. Schematic diagram of the tungsten filament atomizer. Reprinted with Source permission from Ref [273].)...

Zhou, Y., Parsons, P. J., Aldous, K. M., Brockman, P., and Slavin, W. (2001). Atomization of lead from whole blood using novel tungsten filaments in electrothermal atomic absorption spectrometry. Journal of Analytical Atomic Spectrometry 16 82-89. 

The experiment was performed with a quench-and-look approach, whereby the model system was first heated to 673 K and exposed to low amounts of atomic hydrogen produced by dissociating H2 on a glowing tungsten filament. The flux of hydrogen was then terminated, and the clusters were exposed to thiophene at an elevated sample temperature of about 500 K. Subsequently, the model system was... 

Suppose the vapor pressure is adjusted so that the arrival rate. A, is about 2.6 X 10 cesium atoms/cm.Vsec. If the temperature of the tungsten filament is about 550°K., the surface will be covered with more... 

Bosworth and Rideal (67,68), too found with the contact-potential method an increase of the work function by 1.38 volts when nitrogen was adsorbed on tungsten at 90°K. Since the method described in section III,Id, was used, where a second tungsten filament is heated for the emission of thermionic electrons, it is to be expected that in this case, too, N atoms were formed, which reached the cold wire near the hot one and were adsorbed. 

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. 

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]. 

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