Single-crystal orientation

Figure A3.10.15 NFl synthesis activity of different Fe single-crystal orientations [32]. Reaction conditions were 20 atm and 600-700 K.

Fig. 9.17 NFS spectra of guanidinium nitroprusside single crystals recorded at room temperature with single-crystal orientations and thicknesses as indicated. The solid lines result from a least-squares fit using the CONUSS program [9, 10]. (Taken from [48])...

Furnas, T. C., Jr., "Single Crystal Orienter Instruction Manual", General Electric Company, X-ray Department, Milwaukee, (1957). 

We now wish to outline the situations in which nuclei can appear as equivalent for certain magnetic-field (B) orientations chosen relative to single-crystal orientations in magnetic resonance (NMR and EPR) spectroscopic work. This topic has been covered in considerable detail in an earlier publication.12... 

Fleischauer investigated the effect of sputtering molybdenum disulphide onto a substrate of molybdenum disulphide single-crystal oriented so that the surface consisted of basal plane, and found that the sputtered coating also adopted a basal plane orientation. 

Intensity results were collected on a General Electric XRD-5 Spectrogoniometer, equipped with a Single Crystal Orienter and scintillation counter, with use of Cu-/fg radiation (nickel filter and pulse-height analyser). Complete three-dimensional measurements were recorded for 6 74° (corresponding to a minimum interplanar spacing d = 0-80 A), and all 193 independent reflections in this range were measurable. The intensities were corrected for... 

Figure 4. Simulated NMR spectra for a I = 5/2 quadrapolar nucleus with moderate quadrapolar interaction (vq =100 MHz, Cq = 3 MHz, T] = 0), illustrating the effects of the quadrapolar interaction on the satellite and central transitions, a) Single-crystal oriented at 0 = 90° (Eqn. 3). The five peaks correspond to the five possible transitions between the levels (m,m-l) (Fig. 1). b) Randomly oriented powder, calculated from Equation (3) for all possible values of 0 by weighting the intensities proportional to sin(0). 3x vertical exaggeration to show detail in satellite transitions, c) MAS-NMR and d) static (without MAS) powder spectra of the central (1/2,-1/2) transition showing the peak shift and broadening due to second-order effects of the quadrapolar interaction. The full width of the powder pattern in c) can be calculated from Equation 4. Frequency origin corresponds to the chemical shift (5,).

The deformation texture of brass sheet (Fig. 9-19) is fairly sharp, and it is then of interest to know whether or not it can be approximated by an ideal orientation. To find this orientation we successively lay several standard projections over the pole figure, looking for a match between (111) poles and high-density regions. The solid triangles in Fig. 9-19 show such a match they represent the (111) poles of a single crystal oriented so that its (110) plane is parallel to the sheet and the [Tl2] direction parallel to the rolling direction. Reflection of these poles in the... 

Atomic configurations of some Cu crystal orientations are unstable, and easily reconstmcted during surface pretreatment, e.g. by the presence of oxygen and ultrasonic rinsing in the pretreatment procedme and so on. Cu(llO) is particularly vulnerable among various Cu single crystal orientations, and the selectivity in CO2 reduction on Cu(llO) is hardly reproducible. Takahashi et al. 

A Kamlowski A Van der Est PFromme and D Stehlik (1997) Low-temperature EPR on photosystem I single crystals orientation of the iron-sulfur centers Fp andFg. Biochem Biophys Acta 1319 185-198... 

A Ni(lll) single crystal, oriented to within 0.2° of the (111) plane, is mounted on a manipulator which rotates it 360° around an axis parallel to its surface and translates it in three mutually perpendicular directions while maintaining the ultrahigh vacuum conditions in the main chamber. The crystal can be cooled to 8 K by contact with a liquid He reservoir and can be heated to 1400 K. A chromel-constantan thermocouple is spot-welded to the crystal for temperature measurements. The procedure for cleaning the crystal by Ar ion sputtering, oxidation and reduction has been discussed previously (ref. 5). 

A more elaborate method allows the full elasticity tensor of cubic crystals to be determined, with arbitrary orientation, in a DAC. This requires measurements at several angles from the cell s axis over a large angular span (180°) and it therefore necessitates large (>90°) optical apertures. A fit of the observed velocities allows both the single-crystal orientations and the full set of elastic coefficients to be determined. 

These statements can be visualized by the schemes on the following page. In a series of papers by Baltruschat et al., the influence of the Pt single crystal orientation on the electrocatalytic hydrogenation of benzene and the H-D exchange in its adsorbed state and the electrochemical stability of adsorbed benzene, aniline and pyridine on mono- and polycrystalline Pt, Rh, and Pd electrodes was studied. 

A germanium single crystal, oriented along the (111) plane, was used as a monochromator. The careful selection of a germanium crystal with a high reflectivity and improvements in the factory-built monochromator unit increased the intensity by a factor of 2.0—2.5. 

Fig. 2. Photomicrographs of the opposite surfaces of a GaAs single crystal oriented in the [111] direction after etching in a 1.5 JV solution of iron (HI) chloride in 2.0 N perchloric acid, a) A surfaces (x 120) b) B surfaces (x 340) c) A surfaces of a single crystal with an appreciable deviation from orientation in the [111] direction (x 70).

The irradiation of alcohols, acids, amides, fluorocarbons, and other compounds has provided other radicals for study. Work on single crystals oriented in magnetic fields yielded the spectroscopic data for the perfluorosuccinate, XX, and the perfluoropropionamide, XXVI (51,56). The study of unoriented materials has yielded additional information concerning the coupling behavior of a-and /3-fluorine atoms in perfluoromethylcyclohexyl radical, XXVII, hydroxyalkyl derivatives, XXVIII, the perfluoroglutarate, XXIX (57,58) as well as the 2,2,2-trifluoroethyl radical (59) and other related substances (54). 

The first xSR studies were carried out on textured polycrystals and concentrated on the paramagnetic state (Barsov et al. 1983, 1986c). Hartmann et al. (1990c) and Wappling et al. (1993) extended those studies to a single crystal oriented with its c-axis both... 

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