Powder pattern measure

Single crystals, crystalline, or amorphous powders and whole biological systems have been studied in the solid state by means of NMR spectroscopy. The proton-decoupled NMR powder pattern, measured in the solid state without rotation of a... 

For a single powder pattern, measuring Avq is equivalent to measuring any of the moments. If there is more than one quadru-pole splitting in the system, is proportional to the statistical average of (Avq), The average order can be determined the width of its distribution may be defined by eq. 15 (13). If... 

Position Sensitive Detectors. By replacing the scintillation detector in a conventional powder diffractometer with a Position Sensitive Detector (PSD), it is possible to speed data collection. For each x-ray photon received a PSD records the angle at which it was detected. Typically, a conventional scintillation detector records x-ray photons in a range of a few hundredths of a degree at a time. A PSD can measure many degrees (in 20) of a powder pattern simultaneously. Thus, for small samples, data collection, which could require hours with a conventional detector, could take minutes or even seconds with a PSD. 

Figure 15-6. (a) Phoioiuduccd absorption-detected magnetic resonance (ADMR) spectrum of MEH-PPV. HF and FF represents tire half field and full field powder pattern for the triplet (S=l) resonance, respectively, (b) ADMR spectrum ol MEH-PPV/CW, composite film. Both spectra were measured at probe energy 1.35 eV, T=4 K and 3 GHz resonant microwave frequency (reproduced by permission of the American Physical Society from Ref. 1191). 

Another example comes from the work of Johnson, et a/.18 These workers studied spin labels dissolved in lipid bilayer dispersions of dipalmitoylphos-phatidylcholine and cholesterol (9 1 by weight) in the hope that anisotropic rotational diffusion of the spin label would mimic the motion of the bilayer components. In addition to 5-DS, which is sensitive to rotational motion about the NO bond, they used the steroidal nitroxide 8, which tends to rotate about an axis perpendicular to the N-O bond. ESR measurements were carried out at both 9 and 35 GHz and at temperatures ranging from 30 to 30 °C. Rather different results were obtained with the two spin labels, largely as a result of the different axes of rotation. Because the rotation rates were very slow, ESR spectra appeared as powder patterns rather than isotropic spectra and special methods were needed to extract the motional data. 

XRD powder patterns of fresh and used catalysts, measured at room temperature on a Bruker D8 Advance diffractometer equipped with Sol-X detector, were subjected to Rietveld structure refinement in Immm space group using the GSAS package (Larson and Von Dreele, 1994). 

To measure a powder pattern, a randomly oriented powdered sample is prepared so as to expose all possible planes of a crystalline powder. The scattering angle, 6, is measured for each family of crystal planes by slowly rotating the sample and measuring the angle of diffracted x-rays... 

Figure 48 shows representative experimental 2H NMR spectra from the labeled retinal in bR in a dark-adapted PM sample. The line shape simulations that were generated in the data analysis are superimposed on the experimental spectra. The powder pattern [Figure 48(a)] serves as a general reference for the tilt series of spectra recorded at various sample inclinations [Figure 48(b)], because it defines the accessible frequency region over which the spectral intensity can occur. The oriented sample was measured at every 22.5° between 0° and 90°, of which three inclinations are represented in Figure 48(b) with a = 0°, 45° and 90°. 

Fig. 2 Solid state F-NMR spectra of GS-3/3 in oriented DMPC bilayers, measured at 25 °C according to published procedures [17-19,22]. Samples are prepared with a peptidedipid molar ratio of 1 80 (A), 1 40 (B), and 1 20 (C). The arrows indicate the signals emerging at high peptide concentration, corresponding to a new re-aligned state of the peptide. The dashed line shows respective powder pattern of the lyophUized peptide...

X -Ray powder pattern studies of the complexes [M(phen)2X2]" and [M(bipy)2YZ]"+ [M = Co, Rh, Ir, or Os X = Cl, H2O, or ox YZ = CI2 or (0H)(H20)] show that each metal in each series is isomorphous. A cis configuration is therefore assigned to all complexes. Luminescence quantum yields have been measured for a series of [IrCl2(N—N)2C1 complexes (N—N = phen or bipy, or diphenyl derivatives), permitting a quantitative estimate of the effect of ligand phenyl substituents.A normal-co-ordinate analysis (i.r. has been carried out for [Ir(NH3)5Cl]Cl2. ... 

X-ray diffraction powder patterns were recorded on a CGR Theta 60 instrument, using monochromated CuKa radiation. The adsorption capacities for several adsorbates were measured at room temperature by gravimetry, using a Cahn RH microbalance as proposed by Vaughan and Lussier (3 ). The samples were first treated in air for 5 hours at 480°C. The experiment was performed by passing, over the sample, a stream of nitrogen saturated by the vapor pressure of the sorbate at room temperature, the relative pressure P/Po was then equal to 1. 

Scheme 3 The solid yielded by mechanical mixing of the reactants can be used to seed crystal growth from solution to obtain crystals for single-crystal X-ray diffraction experiments. This procedure allows one to compare the X-ray powder diffraction pattern measured on the mechanochemical sample with that calculated on the basis of the single-crystal experiment for the solids obtained by crystallization via seeding of a solution of the ground powder of the adduct...

In a high symmetry crystal system, very few peaks occur in the powder pattern, and they are often well resolved and well separated. It is then possible to measure their position and intensity with accuracy, and by the methods we described earlier, index... 

An example of solid solution formation by separate deposition of binary layers followed by annealing to interdiffuse the two layers is given for Cu3BiS3 deposition [32]. Bi2S3 (film thickness ca. 90 nm) was deposited at room temperature from a Bi(N03)3/triethanolamine/thioacetamide bath onto glass slides. CuS (300-600 nm thick) was then deposited on this film from a CuCli/tri-ethanolamine/ammonia/NaOH/thiourea bath at room temperature. The films were annealed at 250°C for 1 hr. Formation of the CusBiSs phase could be seen from the XRD pattern. Measurement of precipitated powders (prepared by putting the Bi2S3 precipitated in the first deposition in the CuS deposition solution) annealed at 300°C showed more clearly the formation of the solid solution. 

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