Reflection index

Note that parallel lines b and c have the same set of indices. Similarly, in three-dimensional lattices, planes with the same sets of indices are parallel a beam of x-rays striking one plane at an angle permitting diffraction must strike all planes having the same set of indices at the same angle, also permitting diffraction. 

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Characterization of Interlayer Water. X-ray diffraction studies of the 10A hydrate show no hkl reflections indicating a lack of regularity in the stacking of the kaolin layers. In addition to the 10A hydrate, two other less hydrated kaolinites were synthesized. Both have one molecule of water for each formula unit in contrast to the 10A hydrate which has two. These less hydrated clays consequently have smaller d(001) spacings of 8.4 and 8.6 A. The synthesis conditions for these two hydrates are described in (22.). By studying the interlayer water in the 8.4 and 8.6A hydrates, it was possible to formulate a model of the water in the more complicated 10A hydrate. 

Acoustic reflectance achieved by the measurement of the intensity of the reflection of a wave emitted at frequencies between 50 and 150MHz. A greater proportion of reflectance indicates widespread heterogeneity, as for example in fill, in coarse soil types, in highly fractured rock, or sometimes in cases of organic liquids present in the pore space. 

Figure 2. Initial zone [100] of aerinite (left hand side) with 1/b = 14.612 A / a= 90° and 1/c = 2.611 A 2 = 5.222 A where every odd line in c direction is extmcted Zone [410] at tilt about c of 14° (right hand side) exhibits ghost reflections indicated by black arrows.

Data processing occurs in two stages. Initially, diffraction images are reduced to a tabulation of reflection indices and intensities or, after truncation, structure factors. The second stage involves conversion of the observed structure factors into an experimental electron density map. The choice of how to execute the latter step depends on the method used to determine the phase for each reflection. The software packages enumerated above generally focus on exploitation of anomalous signals to overcome the phase problem for a protein of unknown structure. 

TEM and differential X-ray line broadening (expressed by the ratio of the width at half height of the 104 relative to that of the 110 reflection) indicate that the thickness of the platy Al-hematite crystals decreases as Al/(Fe-t Al) increases (Schwertmann et al., 1977 Barron et al., 1984). It is this change in morphology, rather than the structural Al, which governs the IR spectra, in particular the shape factor and the absorp-... 

In examining a list of X-ray reflections for this purpose, it is best to look first for evidence of the lattice type—whether it is simple (P) or compound systematic absences throughout the whole range of reflections indicate a compound lattice, and the types of absences show whether the cell is body-centred (/), side-centred ( 4, P, Or C), or face-centred (F). When this is settled, look for further absences systematic absences throughout a zone of reflections indicate a glide plane normal to the zone axis, while systematic absences of reflections from a single principal plane indicate a screw axis normal to the plane. The result... 

The XRD patterns of the organically functionalized Ti-substituted samples from which the surfactant was removed by the acid treatment exhibited d100, d110 and d200 reflections, indicating a hexagonal arrangement of channels. 

Figure 2 illustrates the X-ray powder diffraction patterns for the as -synthesized and the calcined heterostructures. Both diffraction patterns show a 001 reflection indicating the presence of a layered structure with a basal spacing 36.8 A respectively 32.9 A. However, a decrease of 4 A in the gallery height, along with a small loss of crystallinity, can be observed upon calcination. 

Alternatively, actual distances, rather than reflection indices, can be measured in reciprocal space. Because the dimensions of reciprocal space are the inverse of dimensions in the real space of the crystal, distances in reciprocal space are expressed in the units A 1 (called reciprocal angstroms). Roughly speaking, the inverse of the reciprocal-space distance from the origin out to the most distant measurable reflections gives the potential resolution of the model that we can obtain from the data. So a crystal that gives measurable reflections out to a distance of 1/(3 A) from the origin should yield a model with a resolution of 3 A. 

Figure 3.28 Waveguide network consisting of a single scattering junction to which Nwaveguides are attached. Each waveguide is terminated by an ideal non-inverting reflection, indicated by a black dot [Smith and Rocchesso, 1994].

Figure 3. Electron diffraction patterns from fibrillar fragments of a PBT fiber exhibiting different degrees of order. The arrow points toward the reflection used for DF imaging. Note the splitting of this reflection, indicating a higher degree of order as compared to the same reflection in the pattern of Figure 2.

Mo are single phase, supersaturated solid solutions having an fee structure very similar to that of pure Al. Broad reflection indicative of an amorphous phase appears in deposits containing more than 6.5 atom% Mo. As the Mo content of the deposits is increased, the amount of fee phase in the alloy decreases whereas that of the amorphous phase increases. When the Mo content is more than 10 atom%, the deposits are completely amorphous. As the Mo atom has a smaller lattice volume than Al, the lattice parameter for the deposits decreases with increasing Mo content. Potentiodynamic anodic polarization experiments in deaerated aqueous NaCl revealed that increasing the Mo content for the Al-Mo alloy increases the pitting potential. It appears that the Al-Mo deposits show better corrosion resistance than most other aluminum-transition metal alloys prepared from chloroaluminate ionic liquids. 

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