Laue X-ray diffraction

Eig. 1. Laue x-ray diffraction pattern of a single natural graphite crystal. 

Bartunik, H. D., Bartsch, H. H., and Qichen, H. 1992. Accuracy in Laue x-ray diffraction analysis of protein structures. Acfa Crystallogr. A 48 180-88. 

Srajer, V., Ren, Z., Teng, T. Y., Schmidt, M., Ursby, T., Bourgeois, D., Pradervand, C., Schildkamp, W., Wulff, M., and Moffat, K. 2001. Protein conformational relaxation and ligand migration in myoglobin Nanosecond to millisecond molecular movie from time-resolved Laue X-ray diffraction. Biochemistry 40 13802-15. 

A Laue X-ray diffraction pattern from a protein crystal. A stationary crystal is irradiated with very intense white, multiwavelength X rays from a synchrotron source. The diffraction pattern is rich in information. A single 0.1 ms X-ray pulse may provide a pattern with enough information to determine a three-dimensional structure. 

Any symmetry in the intensities in the diffraction pattern other than that implied by Friedel s Law is called Laue symmetry (because it can be displayed on Laue X-ray diffraction photographs of an appropriately-aligned crystal, see Figure 4.16). Friedel s Law implies that there is a center of symmetry in the diffraction pattern. Therefore the Laue symmetry-displayed by the diffraction pattern is the point-group symmetry of the crystal with an additional center of symmetry (if this does not already exist). If a crystal is monoclinic then, the intensities I[hkl) and I hkl) are the same, although I hkl) does not equal I[hkl). Orthorhombic... 

The characterization of the samples which were produced under microgravity and normal gravity have been performed by following methods. Scanning Electron Microscopy ( SEM ) for micro structure. X-ray diffraction and Laue X-ray diffraction for crystal structure, and Auger Electron Spectroscopy (AES ) for compositional analysis, respectively. 

V. Ratnikov, R. Kyutt, T. Shubina, T. Paskova, E. Valcheva, B. Monemar, Bragg and Laue x-ray diffraction study of dislocations in thick hydride vapor phase epitaxy GaN films, J. Appl. Pbys., 88, 6252-6259 (2000). 

Terephthalic acid (TA) is an important industrial chemical used in the production of polyester. Its purification involves multi-stage recrystallization under extreme conditions. The phase characterisation and morphologies of Forms I and II of TA were studied by HSM, thermal analysis, Raman spectroscopy, single crystal Laue X-ray diffraction, lattice energy and morphological calculations [ 157]. Contrary to earlier reports, this study revealed that Form 11 (not Form I) is the thermodynamically stable form of TA under ambient conditions. The apparent stability of Form I was shown to be due to twinning in microcrystals... 

A) An experimental Laue X-ray diffraction pattern on exposed film B) analysis of the experimental pattern... 

Coherent scattering of x-rays from crystalline materials, as outlined earlier, leads to diffraction. Since its discovery in 1912 by von Laue, x-ray diffraction (XRD) has provided a wealth of information about the structure and chemical composition of crystalline materials. For compositional analysis, the technique is unique in that it is the only analytical method capable of providing qualitative and quanti-... 

Since its discovery in 1912 by von Laue, X-ray diffraction has provided a wealth of important information to science and industry. For example, much of what is known about the arrangement and the spacing of atoms in crystalline materials has been determined directly from diffraction studies. In addition, such studies have led to a much clearer understanding of the physical properties of metals, polymeric materials, and other solids. X-ray diffraction is one of the most important methods for determining the structures of such complex natural products as steroids, vitamins, and antibiotics. The details of these applications are beyond the scope of this book. 

Initial assessment of the outcome of a crystal growth experiment is usually carried out by Laue X-ray diffraction. Chemical etching (when possible) can reveal grain boundaries but the extent of a single grain is usually confirmed by XRD. The Laue technique can also provide an indication of crystal quality from the shape and nature of the individual spots. Often this is as far as characterisation proceeds, particularly where the intermetallic compounds are concerned. 

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