Single crystals data analysis

The first detection of the RP state in PS I single crystals was reported by Kamlowski et al.2il using transient EPR at X-band. Berthold et al.2 3 oriented PS I RCs in the B0 field of the W-band spectrometer. From the analysis of the polarization pattern they reproduced the RP geometry obtained in the single crystal data. High field EPR studies proved to be very useful as shown by Stehlik and coworkers who first used K-band EPR144,284, later the work was extended to a multifrequency approach including W-band by van der Est et al.285 and Zech et al.192. In the latter paper a complete analysis of the structure of the RP P 7o0 A -... 

Although the third structure type was established for ruthenium pentafluoride (88), the results were based on restricted single-crystal data, giving less accurate molecular dimensions. Full data were used for the structure analysis of the osmium compound (89 ) but the results were still unsatisfactory, because of the predominant scattering by the... 

ENDOR (Electron Nuclear Double Resonance) involves the simultaneous application of a microwave and a radio frequency signal to the sample. This is a technique invented by Feher in 1956. The original studies were on phosphorous-doped silicon. A description of the experimental results and apparatus used is presented in two Physical Review articles [24, 25], An excellent treatment of EPR double resonance techniques and theory is given in the book by Kevan and Kispert [26], What follows here is the theory and application of ENDOR used the in analysis of single crystal data with the goal of identifying free radical products in DNA constituents. 

At the same time, the structural chemistry of tri- and tetravalent actinide orthophosphates is not well-known. A small number of theoretically possible compounds have been discussed [14]. The collection of information on actinide compounds may take a long period of time, on account of the experimental difficulties of work with actinides that require special conditions and equipment. Consequently, single crystal data are available for a few compounds only in most cases, the analysis was based on powder diffraction data and analogy to other structures. 

Recently the ICDD Powder Diffraction File underwent a substantial and useful upgrade calculated patterns based on single crystal data from the ICSD file have been included into the PDF-2/PDF-4 Full File calculated patterns of structures stored in the CSD file, have been included into the PDF-4 Organics (see Table 4.3). These additions make it possible to conduct searches and find matches with computed digitized powder patterns in addition to experimentally measured powder diffraction data, thus improving automation, simplifying phase identification process and considerably expanding the applicability of the powder method for a qualitative phase analysis. 

A.C. Larson and R.B. Von Dreele, General Structure Analysis System (GSAS), Los Alamos National Laboratory Report, LAUR 86-748 (2000). Although GSAS is suitable for treatment of both powder diffraction and single crystal data, in the context of this book we are chiefly concerned with its capabilities to processing powder data. 

Analyzing the geometry of the model. This approach is nearly always used in molecular compounds, even when single crystal data are available. The analysis involves prior knowledge of possible bond distances, angles, coordination polyhedra, etc. 

Although, the powder method was developed as early as 1916 by Debye and Scherrer, for more than 50 years its use was almost exclusively limited to qualitative and semi-quantitative phase analysis and macroscopic stress measurements. The main reason for this can be found in what is known as the principal problem of powder diffraction accidental and systematic peak overlap caused by a projection of three-dimensional reciprocal space on to the one-dimensional 26 axis, leading to a strongly reduced information content compared to a single crystal data set. However, despite the loss of angular information, often sufficient information resides in the ID dataset to reconstruct the 3D structure. Indeed, quantitative analysis of the pattern using modern computers and software yields the wealth of additional information about the sample structure that is illustrated in Figure 1. Modern... 

An analysis of the magnetic anisotropy in terms of crystal-field interactions was on the basis of single-crystal data obtained on Y18Er02Fe14B by Williams et al. (1988). 

In conclusion, we propose that the properties and characteristics of the phosphate zeolites presented, including single-crystal microprobe analysis, infrared spectra, zeolite framework stoichiometry, and unit cell data, establishes beyond doubt the substitution of phosphorus in zeolite frameworks. 

The microkinetic analysis of the H2 TPD data from Cu catalysts revealed that the influence of readsorption was negligible rendering the mathematically easier CSTR model appropriate. In this case, the proper kinetic desorption parameters can be extracted from the shifting TPD peak maximum temepratures as function of the heating rate. However, the example illustrated that deriving the coverage dependence from single crystal data is not without pitfalls. 

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