Electrodeless discharge, and

Rodebush and Klingelhoeffer measured the rate of the reaction Cl+H2 HCl-f-H by producing atoms in an electrodeless discharge and flowing the Cl into an hydrogen stream. The concentration of Cl atoms was measured with a diffusion gauge of the Wrede type. The HCl produced was collected and subsequently determined by titration. The calculated rate coefficients at 289 °K and 273 °K are... 

Thermochemical data for alkyl amino radicals show for alkylhydrazines a trend in D (N-N) for these compounds in which the N-N bond was strengthened by increasing the degree of substitution by methyl in NH2 NH2 . From these values it was possible to determine values for the enthalpies of formation of the alkylamino radicals , and to confirm these by electron impact studies. The latter values were found to be in agreement with those obtained from pyrolysis studies. Hydrazine has often been used as a source of amino radicals by pyrolysis flame decomposition shock tube decomposition , electrodeless discharge and microwave discharge , viz. 

Christy s theory of polymerization by electron bombardment contains an important idea which can be applied to the theory of direct glow discharge polymerization (3). Williams and Hayes emphasized the importance of monomer adsorption to the electrode in the direct method (4). Poll also described the process of film formation in the direct method (. Yasuda et al. employed the indirect method, using an electrodeless discharge, and the results... 

Electrical units 503, 519 Electrification due to wiping 77 Electro-analysis see Electrolysis and Electrogravimetry Electrochemical series 63 Electro-deposition completeness of, 507 Electrode potentials 60 change of during titration, 360 Nernst equation of, 60 reversible, 63 standard 60, (T) 62 Electrode reactions 505 Electrodeless discharge lamps 790 Electrodes antimony, 555 auxiliary, 538, 545 bimetallic, 575... 

Strong evidence in favor of mechanism B was obtained when it was discovered that singlet oxygen produced chemically by the reaction of hydrogen peroxide and sodium hydrochlorite or from gaseous oxygen excited by an electrodeless discharge yields the same products as the direct photolysis/85-8 ... 

Additionally, advanced tools for special applications are offered, including provisions for parallel reflux, solvent extraction, and hydrolysis, as well as electrodeless discharge lamps for photochemistry (Fig. 3.10). A detailed description of these accessories can be found on the Milestone website [11],... 

UV radiation, certainly not sufficient to disrupt the bonds of common organic molecules. We therefore assume that, essentially, photoinitiation is responsible for a chemical change and MW radiation subsequently affects the course of the reaction. The objective of microwave photochemistry is frequently, but not necessarily, connected to the electrodeless discharge lamp (EDL) which generates UV radiation when placed in the MW field. 

A microwave-assisted, high-temperature, and high-pressure UV digestion reactor has been developed by Florian and Knapp [44] for analytical purposes. The apparatus consists of the immersed electrodeless discharge lamp operating as a result of the MW field in the oven cavity (Fig. 14.8). An antenna fixed to the top of EDL enhanced the EDL excitation efficiency. Another interesting MW-UV reactor has... 

Ideally, the emission line used should have a half-width less than that of the corresponding absorption line otherwise equation (8.4) will be invalidated. The most suitable and widely used source which fulfils this requirement is the hollow-cathode lamp, although interest has also been shown in microwave-excited electrodeless discharge tubes. Both sources produce emission lines whose halfwidths are considerably less than absorption lines observed in flames because Doppler broadening in the former is less and there is negligible collisional broadening. 

Figure S.4 shows a calibration graph of arsenic concentrations obtained by using a Perkin Elmer 2100 atomic-absorption system bnked to a P.S. Analytical hydride/vapour generator (PSA 10.003). An electrically heated tube has been used in this work and the spectral source was an electrodeless discharge lamp. Alternatively, a flame-heated tube can be used.

Mechanisms such as the brush light arc, the charged water bubble, afterglow phenomena, and diffusion combustion of small gas admixts in air have been suggested, and explain one or more features of the phenomenon but fail to explain others. High-frequency electrodeless discharges have some of its features. 

High intensity is not a source requirement in AAS and therefore electrodeless discharge lamps will not replace hollow-cathode lamps. However, for those elements that produce poor hollow-cathode lamps (notably arsenic... 

Where vapour discharge lamp sources exist (for volatile elements such as Hg, Na, Cd, Ga, In, T1 and Zn) they can be used. Hollow-cathode lamps are insufficiently intense, unless operated in a pulsed mode. Microwave-excited electrodeless discharge lamps are very intense (typically 200-2000 times more intense than hollow-cathode lamps) and have been widely used. They are inexpensive and simple to make and operate. Stability has always been a problem with this type of source, although improvements can be made by operating the lamps in microwave cavities thermostated by warm air currents. A typical electrodeless discharge lamp is shown in Fig. 6.3. 

Q. What advantages are offered to AFS by (i) electrodeless discharge lamps and (ii) lasers ... 

By far the most common lamps used in AAS emit narrow-line spectra of the element of interest. They are the hollow-cathode lamp (HCL) and the electrodeless discharge lamp (EDL). The HCL is a bright and stable line emission source commercially available for most elements. However, for some volatile elements such as As, Hg and Se, where low emission intensity and short lamp lifetimes are commonplace, EDLs are used. Boosted HCLs aimed at increasing the output from the HCL are also commercially available. Emerging alternative sources, such as diode lasers [1] or the combination of a high-intensity source emitting a continuum (a xenon short-arc lamp) and a high-resolution spectrometer with a multichannel detector [2], are also of interest. 

Kl4n, P., Literdk, J. and H4jek, M., The electrodeless discharge lamp a prospective tool for photochemistry,... 

---