Argon addition

Fibrous growth of ZrBj occurs under a.c. discharge at 0.5-1 mA, the growth being accelerated by argon addition. Zirconium diboride fibers with a diameter of 9 Lim are obtained ". 

Methylene produced by mercury photosensitized decomposition of 011200 was found to add to cfs-butene-2 to give product ratios similar to those obtained by Frey under conditions of high dilution with argon. Addition of this type of methylene to (rans-butene-2 gave similar product ratios, with the exception that the trans isomers of 1,2-dimethylcyclo-propane and pentene-2 were favored over the cis. These results were taken as proof of the nonstereospecific addition of triplet CH2 to olefins. 

Interesting additional inert gas effects have been observed by Biron and Nalbandjan [17]. Using silica vessels they confirmed the above behaviour but in experiments under conditions analogous to those used by Semenova, already discussed, they found the critical explosion pressures to be unaffected by argon addition. Their results are given in Table 4. The conditions used by Semenova correspond with extremely low chain breaking efficiency at the vessel wall, and under these conditions the rates... 

Isoprene. Matheson pure grade isoprene was passed slowly through 3A molecular sieves into a dry R.B. flask. To this (500 ml) we added 50 ml of a 25% triisobutylaluminum solution in hexane. The isoprene was distilled in a simple distillation setup and collected in 12-oz bottles which are capped and maintained at 10 psi argon. Addition to polymerization bottles was accomplished by syringe. 

Bacri j., Gomes A. M., Fieni J. M., Thouzeau F. and Birolleau J. C. (1989) Transport coeffldent calculation in air-argon mixtures explanation of the improvement of detection limits of pollutants in air inductively coupled plasmas by argon addition, Spectrochim. Acta, Part B 44 887-895. 

The energy released when the process under study takes place makes the calorimeter temperature T(c) change. In an adiabatically jacketed calorimeter, T(s) is also changed so that the difference between T(c) and T(s) remains minimal during the course of the experiment that is, in the best case, no energy exchange occurs between the calorimeter (unit) and the jacket. The themial conductivity of the space between the calorimeter and jacket must be as small as possible, which can be achieved by evacuation or by the addition of a gas of low themial conductivity, such as argon. 

It turns out that the CSP approximation dominates the full wavefunction, and is therefore almost exact till t 80 fs. This timescale is already very useful The first Rs 20 fs are sufficient to determine the photoadsorption lineshape and, as turns out, the first 80 fs are sufficient to determine the Resonance Raman spectrum of the system. Simple CSP is almost exact for these properties. As Fig. 3 shows, for later times the accuracy of the CSP decays quickly for t 500 fs in this system, the contribution of the CSP approximation to the full Cl wavefunction is almost negligible. In addition, this wavefunction is dominated not by a few specific terms of the Cl expansion, but by a whole host of configurations. The decay of the CSP approximation was found to be due to hard collisions between the iodine atoms and the surrounding wall of argons. Already the first hard collision brings a major deterioration of the CSP approximation, but also the role of the second collision can be clearly identified. As was mentioned, for t < 80 fs, the CSP... 

Therefore, if a large quantity of sample is introduced into the flame over a short period of time, the flame temperature will fall, thus interfering with the basic processes leading to the formation and operation of the plasma. Consequently introduction of samples into a plasma flame needs to be controlled, and there is a need for special sample-introduction techniques to deal with different kinds of samples. The major problem with introducing material other than argon into the plasma flame is that the additives can interfere with the process of electron formation, a basic factor in keeping the flame self-sustaining. If electrons are removed from the plasma by... 

In the case of atoms UPS is unlikely to produce information which is not available from other sources. In addition many materials have such low vapour pressures that their UPS spectra may be recorded only at high temperatures. The noble gases, mercury and, to some extent, the alkali metals are exceptions but we will consider here only the specttum of argon. 

Final purification of argon is readily accompHshed by several methods. Purification by passage over heated active metals or by selective adsorption (76) is practiced. More commonly argon is purified by the addition of a small excess of hydrogen, catalytic combustion to water, and finally redistiHation to remove both the excess hydrogen and any traces of nitrogen (see Fig. 5) (see Exhaust control, industrial). With careful control, argon purities exceed 99.999%. 

The most common fused salt baths are complex mixtures of alkah chlorides, rigorously purified and dried. Fused salt plating must be done under an inert atmosphere. Often argon is used because nitrogen can react with some metals. Inert anodes, eg, Pt-coated titanium or graphite, are used and the plating metal is suppHed by additions of an appropriate metal salt. 

Succinic anhydride is stabilized against the deteriorative effects of heat by the addition of small amounts (0.5 wt %) of boric acid (27), the presence of which also decreases the formation of the dilactone of gamma ketopimelic acid (28). Compared with argon, CO2 has an inhibiting effect on the thermal decomposition of succinic acid, whereas air has an accelerating effect (29,30). 

Two colorimetric methods are recommended for boron analysis. One is the curcumin method, where the sample is acidified and evaporated after addition of curcumin reagent. A red product called rosocyanine remains it is dissolved in 95 wt % ethanol and measured photometrically. Nitrate concentrations >20 mg/L interfere with this method. Another colorimetric method is based upon the reaction between boron and carminic acid in concentrated sulfuric acid to form a bluish-red or blue product. Boron concentrations can also be deterrnined by atomic absorption spectroscopy with a nitrous oxide—acetjiene flame or graphite furnace. Atomic emission with an argon plasma source can also be used for boron measurement. 

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