Elements, sources

Fig ure 7-18. Cross-seotion of flanged Kenios Statio Mixer with four helioal mixing elements. (Source Chemineer-Liquid-Agitation.)... 

At present, most high-voltage sources for ordinary spectrographs are designed for a 60-kv maximum, which is too low to excite the K lines of the heavier elements. Sources capable of exciting the K lines of even the heaviest elements can be built, but until recently, only at a considerable increase in cost. For the ordinary laboratory, it has been more economical to use the L lines of the heavier elements, which can be excited below 60 kv, than to invest in a 100-kv source. 

In molecular beam epitaxy (MBE), the constituent elements of the desired film in the form of molecular beams are deposited epitaxially onto a heated crystalline substrate. These molecular beams are typically from thermally evaporated elemental sources (e.g., evaporation of elemental As produces molecules of As2, As3, and As4). A refinement of this is atomic layer epitaxy (ALE) (also known as atomic layer deposition, ALD) in which the substrate is exposed alternately to two... 

The deposition of a wide range of materials using beams of elemental sources in high-vacuum apparatus (10-4—10-8 torr), essentially by physical methods, is known as molecular beam epitaxy (MBE)8 12 and atomic layer epitaxy (ALE). These methods will be mentioned where there is an overlap with CVD techniques, but will not be fully reviewed. (They are mentioned also in Chapter 9.15). 

Metal alkyls 13 A1R3, GaR3, InR3 (R — Me, Et, Pr1, etc.) Matrix element sources for III V alloys... 

Box model for the biolimiting elements. Source From Broecker, W. S. (1974). Chemical Oceanography, Harcourt, Brace and Jovanovich Publishers, pp. 14-15. 

Figure 10.11 Effects of temperature on conventional solid/liquid partition coefficients of various transition elements. Sources of data are also listed.

Factor analysis was used to identify principal types of emission sources and to select elemental source tracers. As factor analysis has been described in detail in the literature (10-13), only a general description of the technique will be given... 

The uneven distribution of the chemical elements in Ihe earth s crust causes severe imbalances in ihctr availability for industrial manufacturing uses. Frequently, the largest consuming nations are long distances from elemental sources, as in the case of the United Slates This clearly indicates the need lor the various political entities of the world to stockpile and lo project (heir... 

Kg- 2. Polar representation of periodic relationships of the elements. (Source Oumibix, U.SAJ) At upper right is shown the conventional representation, see the front matter for the current representation... 

Fig 9 Schematic Illustration of General Cost Element Sources... 

Landsberger, S., Vermette, V.G., Stuenkel, D. et al. (1992) Elemental source signatures of aerosols from the Canadian high Arctic. Environmental Pollution, 75(2), 181-87. 

Table 2.2. Representative compositions of Tuscany magmatic rocks. Numbers in parentheses refer to data obtained on distinct though similar rock samples from the same locality as those analysed for the other elements. Source of data 1) Vollmer (1977) 2) Hawkesworth and Vollmer (1979) 3) Poli et al. (1984) 4) Giraud et al. (1986) 5) Peccerillo et al. (1988) 6) Pinarelli (1991) 7) Conticelli and Peccerillo (1992) 8) Poli (1992) 9) Prosperi-ni (1993) 10) Westerman et al. (1993) 11) Innocenti et al. (1997) 12) De Astis et al. (2000) 13) Conticelli et al. (2002) 14) Dini et al. (2002) 15) Gasperini et al. (2002) 16) Author s unpublished data.

The Presence of S-heterocycles and their Element Sources in the Geosphere... 

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