D-spacing

Figure 2-123. The most coinmon molecular graphics representations of phenylalanine a) wire frame b) capped sticks c) balls and sticks d) space-filling.

The 2-D / -space data set is Fourier transformed, and the magnitude image generated from the real and imaginary outputs of the Fourier transform. 

Figure 2 Several atomic planes and their d-spacings in a simple cubic (sc) crystal (al ...

Interdiffusion of bilayered thin films also can be measured with XRD. The diffraction pattern initially consists of two peaks from the pure layers and after annealing, the diffracted intensity between these peaks grows because of interdiffusion of the layers. An analysis of this intensity yields the concentration profile, which enables a calculation of diffusion coefficients, and diffusion coefficients cm /s are readily measured. With the use of multilayered specimens, extremely small diffusion coefficients (-10 cm /s) can be measured with XRD. Alternative methods of measuring concentration profiles and diffusion coefficients include depth profiling (which suffers from artifacts), RBS (which can not resolve adjacent elements in the periodic table), and radiotracer methods (which are difficult). For XRD (except for multilayered specimens), there must be a unique relationship between composition and the d-spacings in the initial films and any solid solutions or compounds that form this permits calculation of the compo-... 

Angelo, J. A. and Buden, D., Space Nuclear Power. Orbit Book Company, Inc., Malabar, FL., 1985. 

We have found that high molecular weight poly (p-PIN)s readily yields fibers by manual drawing from the melt. X-ray analysis of melt-drawn fibers showed a characteristic amorphous halo with a d spacing at 6.2 A. 

Laguerre polynomials 3-D. /-space 264 eigenfunctions 119, 262-3 Raman and CARS spectra 120 Landau-Teller formula 159 Langevin model equation 32... 

In addition, an interesting, although negative, result has come from powder diffraction studies of the hexachloro compounds. We have examined Debye—Scherrer photographs of several samples known to contain predominantly hexachlorodibenzo-p-dioxins and have identified the patterns of at least three crystalline phases therein. (There are 10 possible isomers of hexachlorodibenzo-p-dioxin.) These patterns have been checked carefully against the calculated d-spacings and intensities of the 1,2,3,7,8,9-hexa isomer described by Cantrell, Webb, and Mabis (I) and also against an observed pattern supplied by Cantrell and believed to be from the low temperature phase of the same material. Yet to date we... 

FIG. 4 Experimental (vertical bars) and simulated (symbols) values of the d-spacings for aUcy-lammonium-exchanged clay at three different cation exchange capacities (CECs) (a) SWy2 mont-morillonite, CEC = 0.8 meq/g (b) AMS montmorillonite (Nanocor), CEC = 1.0 meq/g (c) fluoro-hectorite (Dow-Corning), CEC = 1.5 meq/g. (Erom Ref. 30.)... 

Akelah andMoet [62] followed a modified approach to prepare PS-clay intercalated nanocomposites using a solvent to facilitate intercalation. MMT was ion exchanged using a polymerizable surfactant, vinylbenzyltrimethylammonium chloride. Acetonitrile was found to be the most effective solvent, producing a d-spacing of 2.45 mn versus 2.22 and... 

Given the following "d-spacings" for the diffraction lines of a given cubic powder, calculate the h.k.l values of the pleme spacings. 

All diffraction spots in the aurichalcite mineral calcined at 400°C (Figure 4b) could be attributed to ZnO, except for four weak spots with a d-spacing of 0.192 nm. These spots matched well the Cu0 ll2 reflections with a reported value of d = 0.195 nm (6). Crystalline CuO was found to be present at this stage by XRD, as seen from Figure 3c. 

GL 1] [R 1] [R 3] [P la-d] Space-time yields higher by order of magnitude were found for the falling film micro reactor and the micro bubble column as compared with the laboratory bubble column [38], The space-time yields for the micro reactors ranged from about 20 000 to 110 000 mol monofluorinated product m h. The ratio with regard to this quantity between the falling film micro reactor and the micro bubble column was about 2. The performance of the laboratory bubble column was of the order of 40-60 mol monofluorinated product m" h. ... 

The advantages that accrue from the use of LSMs are manifold. Firstly, these devices are physically robust and can be handled without undue provision. They can be tailored to contain materials of interest and, furthermore, one can vary the d- spacing of the... 

Scattering angle 20 d- spacing (A) Relative intensity (%) Scattering angle 20 J-spacing (A) Relative intensity (%)... 

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