Adsorption cross section

Fig. 6 Yardstick-plot (Eq. 1) of N220 (triangle) and a graphitized N220g (filled circles) with adsorption cross section a determined from the bulk liquid density p (Eq. 2) 1 argon, 2 methane, 3 ethane, 4 propane, 5 iso-butane, 6 n-butane The slopes yield for N220 ds=2.56 0.04, for N220g ds=2.32 0.03. Adsorption temperatures and densities p are chosen according to the evaporation points of the gases at 1000 mbar...

Monoenergetic photons excite a core-hole. The modulation of the adsorption cross-section with energy 100-500 eV above the excitation threshold yields information on the radial distances to neighboring atoms. The cross-section can be monitored by fluorescence as core-holes decay or by the attenuation of the transmitted photon beam. EXAFS is one of many "fine-structure" techniques. This is not intrinsicly surface sensitive (see SEXAFS). 

Fig. 5 Pt clusters for which adsorption cross section calculations were carried out.

Source or sink term or consumption rate of gas species Specific entropy or entropy per unit mass or adsorption cross section of the adsorbing species Molar specific entropy Absolute entropy Change of entropy Change in absolute entropy Temperature High temperature Low temperature Dew point temperature Temperature of product of combustion Saturation temperature Critical temperature Reduced temperature Temperature at inlet of gas channel... 

Ax = adsorption cross section of analyte X, hb = adsorption cross section of solvent molecule, and Nb = number of polar solvent molecules. If the slope representing the number of analyte molecules/number of solvent molecules displaced is large, B is either a very polar solvent and/or the analyte is weakly retained. The converse is true if the slope is small. 

A still different approach to multilayer adsorption considers that there is a potential field at the surface of a solid into which adsorbate molecules fall. The adsorbed layer thus resembles the atmosphere of a planet—it is most compressed at the surface of the solid and decreases in density outward. The general idea is quite old, but was first formalized by Polanyi in about 1914—see Brunauer [34]. As illustrated in Fig. XVII-12, one can draw surfaces of equipo-tential that appear as lines in a cross-sectional view of the surface region. The space between each set of equipotential surfaces corresponds to a definite volume, and there will thus be a relationship between potential U and volume 0. 

Local equihbrium theory also pertains to adsorption with axial dispersion, since this mechanism does not disallow existence of equilibrium between stationary and fluid phases across the cross section of the bed [Rhee et al., Chem. Eng. ScL, 26, 1571 (1971)]. It is discussed below in further detail from the standpoint of the constant pattern. 

The constant pattern concept has also been extended to circumstances with nonplug flows, with various degrees of rigor, including flow profiles in tubes [Sartory, Jnd. Eng. Chem. Fundam., 17, 97 (1978) Tereck et al., Jnd. Eng. Chem. Res., 26, 1222 (1987)], wall effects [Vortmeyer and Michael, Chem. Eng. ScL, 40, 2135 (1985)], channeling [LeVan and Vermeulen in Myers and Belfort (eds.). Fundamentals of Adsorption, Engineering Foundation, New York (1984), pp. 305-314, AJChE Symp. Ser No. 233, 80, 34 (1984)], networks [Aviles and LeVan, Chem. Eng. Sci., 46, 1935 (1991)], and general structures of constant cross section [RudisiU and LeVan, Jnd. Eng. Chem. Res., 29, 1054 (1991)]. 

By using an anionic collector and external reflux in a combined (enriching and stripping) column of 3.8-cm (1.5-in) diameter with a feed rate of 1.63 ni/n [40 gal/(h ft )] based on column cross section, D/F was reduced to 0.00027 with C JCp for Sr below 0.001 [Shou-feld and Kibbey, Nucl. AppL, 3, 353 (1967)]. Reports of the adsubble separation of 29 heavy metals, radioactive and otheiwise, have been tabulated [Lemlich, The Adsorptive Bubble Separation Techniques, in Sabadell (ed.), Froc. Conf. Traces Heavy Met. Water, 211-223, Princeton University, 1973, EPA 902/9-74-001, U.S. EPA, Reg. 11, 1974). Some separation of N from by foam fractionation has been reported [Hitchcock, Ph.D. dissertation. University of Missouri, RoUa, 1982]. 

Based on the gas adsorption behavior, Ko-zawa and Yamashita proposed a hypothesis [20, 21] that the cross—section of the fine pores of EMD is a cavity shape as shown in Fig. 16. The cross-section of the pore by computer calculation is a circle (Fig. 16A). Nobody knows the real shape of the cross-section as yet. Kozawa s belief in the cavity shape (Fig. 16B) is based on the results of experiments involving the oxygen adsorbed and desorbed from the pore walls [20]. 

Since the diameters of both kinds of particles are about 200 mn, the thickness of a 10-layer assembly should be about 1.8 p,m. However, the cross section of a sample subjected to 10-fold dipping indicates a thickness of only 1.2 jim (Fig. 21). Similar observations were made by others [94,97] and can be ascribed to the low substrate coverage reached in each of the dipping steps. Serizawa et al. [97] used the second approach and determined the adsorption using QCM and SEM. An SEM image after two adsorption steps indicated a very irregular, amorphous structure, in agreement with Fulda and coworkers [93]. 

The basic technique involves physical adsorption of N2, which has a cross-sectional area of 0.162 nm, on the surface. The problem is that multi-layers of gas start to build up on the catalyst surface before a monolayer is completely formed. The BET equation describes these phenomena ... 

Molecule (cross section/A ) Kinetic diameter/A Pressure /Torr (P/PO) Temp. /K Amoimt of adsorption /pmol g-sohd Cs2.1 Cs2.2 Cs2.5 Ratio ... 

In order to calculate particle size distributions in the adsorption regime and also to determine the relative effects of wavelength on the extinction cross section and imaginary refractive index of the particles, a series of turbidity meas irements were made on the polystyrene standards using a variable wavelength UV detector. More detailed discussions are presented elsewhere (23) > shown here is a brief summary of some of the major results and conclusions. 

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