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High vacuum system

In order to estimate an acceptable air inleakage rate for sizing a vacuum pump for use in the medium to high vacuum system, consider ... [Pg.369]

FIG. 1. Schematic picture of the cocondensation-high-vacuum system for the generation of gaseous MX species and their trapping in a matrix of an organic solvent. [Pg.239]

The decomposition of formic acid over evaporated Pd-Au alloy films has been studied by Clarke and Rafter (69) the same reaction on Pd-Au alloy wires was studied by Eley and Luetic (128). The alloy films were prepared in a conventional high vacuum system by simultaneous evaporation of the component metals from tungsten hairpins. The alloy films were characterized by X-ray diffraction and electron microscopy. The X-ray diffractometer peaks were analyzed by a method first used by Moss and Thomas (SO). It was found that alloys deposited at a substrate temperature of 450°C followed by annealing for one hour at the same temperature were substantially homogeneous. Electron microscopy revealed that all compositions were subject to preferred orientation (Section III). [Pg.159]

Fig. 10. Apparatus for the sublimation of decaborane. (A) cold finger (B) ground-glass joint for connection to high-vacuum system (C) high-vacuum stopcock ... Fig. 10. Apparatus for the sublimation of decaborane. (A) cold finger (B) ground-glass joint for connection to high-vacuum system (C) high-vacuum stopcock ...
The distilling flask, collection flask, and column are continuously evacuated with a high-vacuum system. When the bulk of the pentane and residual hexane have distilled away, the temperature of a silicone oil bath surrounding the distillation flask is raised from room temperature to 125° over about a one-hour period. When the distillation rate diminishes appreciably, the temperature is slowly raised to 150° and maintained there until no more liquid is obtained. The distillation flask is cooled to room temperature before air is admitted to the system. The distilled product weighs 86.5 g. (89% yield checkers report 89 %t) and melts at 32 to 32.5°. In this state of purity, (bromomethyl)-carborane is suitable for most uses, but it may be further purified by crystallization from pentane or methanol. For example, crystals obtained by chilling a solution of 86.5 g. of the car-... [Pg.103]

In high-vacuum systems, the limit pressure p( is usually controlled by the degassing rate (<2 ) that decreases with time. [Pg.27]

The crude product is then transferred to an apparatus suitable for distillation of solids (Note 6), and this is joined to a high-vacuum system capable of a vacuum in the range of 10 2 5 mm. Distillation begins when the bath temperature reaches about 190° a boiling point of around 120° is usually observed. When the distillate first begins to appear brown rather than violet, the distillation is stopped immediately (Note 7). The crystalline distillate (ca. 70 g.) is dissolved in 20 ml. of hot ethanol, filtered while hot, and allowed to cool. The solid (about 60 g. of crystals, m.p. 74—76°) is recrystallized from 20 ml. of ethanol to yield 47-53 g. (43-49%) of 4,6,8-trimethylazulene as dark-violet plates, m.p. 80-81° (Note 8). [Pg.49]

Low pressure studies Adsorption of CO. The experiments were performed in an ultra-high vacuum system described previously (1). The data obtained on palladium particles with a size smaller than 2 nm or larger than 3 nm will be discussed in turn. [Pg.432]

Phials of anhydrous perchloric acid in methylene dichloride were made up as described [11]. Sodium ethoxide was prepared i.vac. from purified ethanol and sodium purified by cascade fusion . Solutions of it in diethyl ether were prepared and filled into phials [11,12] by standard techniques on a tapless, jointless high-vacuum system. These solutions were colourless, whereas those prepared i.vac. from vacuum-distilled sodium were always yellow or brown. [Pg.741]

Why must a mass spectrometer utilize a sophisticated high-vacuum system ... [Pg.295]

A high-vacuum system is needed so that the components of air will not be fragmented and cause an interference. [Pg.529]

The volatility of phosphorus trichloride, ethylphosphonous dichloride and sulphuryl chloride, permit of their quantitative transfer in a high-vacuum system. The conversion of the phos-phonous into the phosphonic dichloride can also be carried out in an enclosed system.5... [Pg.123]

The probable impurities in radioactive phosphorus trichloride are hydrogen chloride and phosphorous acid the trichloride is, therefore, purified by fractional evaporation and fractional condensation in the high-vacuum system. Pure ethylphosphonous dichloride is prepared according to the equation ... [Pg.123]

The reaction vessel is attached to the high-vacuum system, and the phosphorus trichloride transferred to it without loss and without risk. Further to reduce the hazards, a powerful magnetic stirrer is employed. The ethylphosphonous dichloride is then oxidized in benzene solution in a vessel connected directly to the vacuum system. [Pg.124]

Another approach is to perform ex situ reactions and insert the sample into a high vacuum system without exposure to ambient conditions. Incorporating N2 glove boxes or reactor systems with X-ray photoelectron spectroscopy (XPS) sample handling can also provide information that is closer to operational conditions. In a similar manner ex situ reactions and sample handling are starting to be apphed to electron microscopy studies. Commercially available sample transfer systems will accelerate the application of this methodology. [Pg.159]

Ions, formed in the source, are transported into the high-vacuum system of the mass spectrometer by the use of a nozzle-skimmer arrangement. This acts as a momentum separator and heavier sample molecules tend to pass through, while lighter solvent and drying gas molecules can be more readily pumped away in this... [Pg.153]

Therefore, in UFIV (p < 10 mbar) the monolayer formation time is of the order of minutes to hours or longer and thus of the same length of time as that needed for experiments and processes in vacuum. The practical requirements that arise have become particularly significant in solid-state physics, such as for the study of thin films or electron tube technology. A UFIV system is different from the usual high vacuum system for the following reasons ... [Pg.65]

Thus the Freon loss comes to = 6.5 -10 mbar - l/s. According to the rule of thumb for high vacuum systems given below, the refrigeration system mentioned in this example may be deemed fo be very tight. Additional conversions for are shown in Tables Vila and VIlb in Chapter 9. [Pg.110]

Where a vacuum is present inside the test specimen (p < 1 mbar), atmospheric pressure outside, and helium is used at the test gas, one refers to standard helium conditions. Standard helium conditions are always present during helium leak detection for a high vacuum system when the system is connected to a leak detector and is sprayed with helium (spray technique). If the specimen is evacuated solely by the leak detector, then one would say that the leak detector is operating in the direct-flow mode. If the specimen is itself a complete vacuum system with its own vacuum pump and if the leak detector is operated in parallel to the system s pumps, then one refers to partial-flow mode. One also refers to partial stream mode when a separate auxiliary pump is used parallel to the leak detector. [Pg.113]


See other pages where High vacuum system is mentioned: [Pg.1770]    [Pg.298]    [Pg.77]    [Pg.372]    [Pg.294]    [Pg.307]    [Pg.19]    [Pg.26]    [Pg.163]    [Pg.125]    [Pg.110]    [Pg.181]    [Pg.228]    [Pg.56]    [Pg.57]    [Pg.79]    [Pg.103]    [Pg.88]    [Pg.161]    [Pg.80]    [Pg.152]    [Pg.73]    [Pg.74]    [Pg.201]    [Pg.505]    [Pg.312]    [Pg.155]    [Pg.29]    [Pg.259]    [Pg.307]    [Pg.99]   
See also in sourсe #XX -- [ Pg.113 ]




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General structure of a high vacuum system

High vacuum

High vacuum process systems

High-Vacuum Pumping Systems

Ultra-high vacuum system

Vacuum system

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