Scattering and diffraction methods

Particle size is the most important parameter in practical applications of powder particles. Usually, powder is constituted by particles of various sizes therefore, it is necessary to obtain not only the mean particle size but also the size distribution. Recently, methods for particle size analysis have been greatly developed, especially analytical techniques with rapid response, high repeatability, and covering a wide range of particle sizes, as in the case of the laser scattering and diffraction methods. 

In addition to scattering and diffraction methods for structure determination, important experimental probes for intrinsic properties are vibrational and rotational spectroscopy. Rotational spectra will be affected by a relativistic reduction of bond length, which will reduce the moments of inertia. This lowers the rotational constant, and we should expect a relativistic red-shift of the rotational spectrum. For vibrational spectroscopy, the situation is less clear— relativistic effects may strengthen as well as weaken bonds. Thus effects of relativity on vibrational spectroscopy depend very much on the system under consideration. A further discussion of these effects is therefore postponed to chapter 22. For the diffraction and scattering techniques, relativistic effects are absorbed into atomic scattering parameters and structure factors and are thus not a primary concern of relativistic quantum chemistry. 

The adsorption of rare gases has been extensively studied experimentally using thermodynamic and calorimetric methods and also scattering and diffraction methods. Nevertheless, the large number of results have not always been interpreted in the same way, and serious discrepancies are to be found, especially in the study of phase transitions. 

Order and polydispersity are key parameters that characterize many self-assembled systems. However, accurate measurement of particle sizes in concentrated solution-phase systems, and determination of crystallinity for thin-film systems, remain problematic. While inverse methods such as scattering and diffraction provide measures of these properties, often the physical information derived from such data is ambiguous and model dependent. Hence development of improved theory and data analysis methods for extracting real-space information from inverse methods is a priority. 

Another optical technique, called the back-light scattering (Kossel-diffraction) method can also be used to investigate structure in food emulsions and foams. In this method, the emulsion (or foam) in a transparent vessel is illuminated by a collimated laser beam (See... 

Kahn, R., Fourme, R., Bosshard, R., Wery, J.P., Dideberg, O., Risler, J.L., Brunie, S. and Janin, J. (1984) Symposium on New Methods in X-ray Absorption Scattering and Diffraction for Applications in Structural Biology, Bristol. 

Laggner P FEBS Advanced Course Structure and Dynamics of Membrane Lipids April 1984, Zeist, Holland Symp. on New Methods in X-Ray Absorption, Scattering and Diffraction for Applications in Structural Biology , Aug. 1984, Bristol U.K. Chance B, Barttmik HD (eds) (1986) Academic Press, London... 

Moffat K, Bilderback D, Schildkamp W, Szebenyi D, Loane R (1986) In Chance B, Bartunik HD New methods in x-ray absorption, scattering and diffraction. Academic Press, New York, p 125... 

Therefore, knowledge of these scattCTing and spectroscopic methods applied to ionic solutions is quite useful for clay-water-ion interface simulations. They discussed the utility of the computational results directly comparable to the scattering and spectroscopic methods. These includes radial distribution function comparison (MD or MC with X-ray or neutron diffraction methods), angular distribution of water molecules around ions (MD or MC with neutron diffraction measurements), self-diffusion coefficient of water and ions (MD with quasi-elastic neutron scattering and NMR measurements), and intramolecular vibrations (flexible potential MD with IR or Raman spectroscopic data). 

The molecular origin of observed deformation mechanisms have been elucidated by various spectroscopic methods — including mechanical relaxation spectroscopy — and by the previously listed tools which characterize the morphology. They are supplemented by dynamic scattering and diffraction techniques [52, 53]. 

The methods used to characterise polymers are partly familiar ones like X-ray diffraction, Raman spectroscopy and electron microscopy, partly less familiar but widespread ones like neutron scattering and nuclear magnetic resonance, and partly... 

We report here the results of our recent studies of poly(alkyl/arylphosphazenes) with particular emphasis on the following areas (1) the overall scope of, and recent improvements in, the condensation polymerization method (2) the characterization of a representative series of these polymers by dilute solution techniques (viscosity, membrane osmometry, light scattering, and size exclusion chromatography), thermal analysis (TGA and DSC), NMR spectroscopy, and X-ray diffraction (3) the preparation and preliminary thermolysis reactions of new, functionalized phosphoranimine monomers and (4) the mechanism of the polymerization reaction. 

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