Some Applications of Vacuum Technology

Some Applications of Vacuum Technology For t < /a, Equation (6.32) must be used ... 

In vacuum technology, some calculations involve the steady flow of fluid through duct of changing circular cross-section (diffusers, jets, nozzles, etc.) and the methods of gas dynamics can be applied to calculate pressures, velocities and temperatures. (A criterion for the applicability of gas dynamics is that Kn < 0.01 although, according to ref. (d), the methods can be applied even at Kn values up to 0.3.)... 

Careful application of some new experimental techniques promises advances in the elucidation of the relation between detailed surface structure and reactivity in the chemisorption of a gas on a metal. Among these experimental techniques are the field-emission microscope (1-3), the inverted ionization gage (4), and modern high-vacuum technology (5). The use of the field-emission microscope technique for the study of the adsorption of oxygen (6) on tungsten has yielded recently data on the surface mobility... 

Because of the experimental difficulty of the technique and because more user-friendly and to some extent more powerful alternatives have become available, FDI is not frequently applied anymore, except for some specific applications. In this respect, an important development is liquid injection field desorption ionization (LIFDI), which enables sample application to the emitter without breaking the vacuum (see Fig. 7.1) [7, 8]. The specific applications where FDI and LIFDI are still applied comprise the analysis of some oiganometallic compounds [9,10], ionic liquids [11], and compound classes, such as (cyclo)paraffins, aromatic hydrocarbons, and nonpolar sulfur compounds (thiophenes) [7, 12-14], not readily amenable to ESI or MALDI. For such nonpolar analytes, mainly molecular ions M+ are observed, whereas for some more polar compounds, [M+H]+ and/or sodiated molecules ([M-l-Na] ) may be observed, e g., for glycosides (Sect. 7.5.2), lipids (Sect. 7.5.4), and peptides (Sect. 7.5.5). A detailed overview on technology and applications of FDI-MS was provided by Schulten et al. [15, 16]. 

The US Techni-Met Inc., has developed a process which may benefit some electronic applications where surface quality is paramount. The process involves the use of vacuum-sputtering technology and an acrylic monomer to lay down an acrylic polymer surface on film. The acrylic bonds to the film substrate by crosslinking and suitable films for the process include PET, PEN, PVC and polyimide. The company claims that its process confers superior water, oxygen and optical properties. 

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