Grazing Incidence Diffraction

XRD patterns from polymers can be analyzed at various levels, based on the quality of the data and the intended use of the results. Earlier efforts were focused on determining the crystal structure, lamellar morphology, and in improving the methods to determine the crystallinity and orientation. Later efforts were focused on determining the nature of the lattice distortions and the nature of the noncrystalline phases. With the availability of synchrotrons, fast 2D detectors, software tools to analyze the data, future effort will more likely be toward understanding the evolution of these structures with time and temperature. While the analysis and interpretation of WAXS data is now straightforward, there is opportunity to improve the analysis and interpretation of the SAXS data. 

Alexander LE. X-Ray Diffraction Methods in Polymer Science. NY Wiley-Interscience 1969. p 582. 

Kakudo M, Kasai N. X-Ray Diffraction by Polymers. Tokyo Kodansha 1972. 

SpruieU JE, Clark ES. Unit ceU and crystallinity. Methods Exp Phys 1980 16 1-127. 

Wang JI, Harrison IR. Crystallite size and lamellar thickness by X-ray methods. Methods Exp Phys 1980 16 128-184. 

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For the case of surface truncation rods, the technique is based on the detection of diffraction peaks between Bragg peaks. Although this requires careful alignment and some a priori knowledge of the structure, monolayer sensitivity can be achieved. In fact, Samant et a/.138 have recently performed an in situ surface diffraction study of lead underpotentially deposited on silver employing this technique along with grazing incidence diffraction. It is clear that this technique will also find widespread use in the near future. 

SAXS is sensitive to variations in the electronic density in a material, and so provides information about the shape and size of clusters in micro PS. In contrast to the quantum wire structure proposed in early publications [Cal, Lei], the crystallites in micro PS are found to be almost spherical. There has been some evidence that the dimensions in the growth direction are somewhat smaller than those parallel to the surface [Fr2], The latter result, however, is still controversial because investigations by spectroscopic techniques indicate an opposite elongation [Mi4], A combination of grazing incidence diffraction (GID) and SAXS measurements on various freestanding micro PS films showed crystallite diameters from about 1.5 to 4 nm, depending on formation conditions. A good correlation between size reduction and blue shift of the PL peak position has been observed [Bi3],... 

X-ray grazing incidence diffraction Lateral ordering in crystalline parts of monolayers (molecular lattice characteristics and average crystallite size) tilt angles and tilt directions. Structural information across the interface limited tilt angles and directions only obtainable using simple models for the molecular shape of the amphiphiles. 

B. Berge, P.-F. Lenne and A. Renault, X-ray grazing incidence diffraction on monolayers at the surface of wate, in Curr. Opinion Colloid Interface Sci. 3 (1998) 321, (Short update.)... 

C. Gliss, H. Clausen-Schaumann, R. Gunther, S. Odenbach, O. Randl, and T. M. Bayler Direct detection of domains in phospholipid bilayers by grazing incidence diffraction of neutrons and atomic force microscopy. Biophys. J., 1998, 74, 2443-2450. 

Kuhl TL, Majewski J, Howes PB, Kjaier K, von Nahmen A, Lee KYC, Ocko B, Israelachvili JN, Smith GS (1999) Packing stress relaxation in polymer-lipid monolayers at the air-water interface an X-ray grazing-incidence diffraction and reflectivity study. J Am Chem Soc 121 7682-7688... 

We then performed in situ X-ray reflectivity and grazing incidence diffraction (GID) measurements to study the thermal stability of these samples. Figure 9.13 shows the reflectivity (a) with the first order DIP Bragg peak (b) for different temperature steps. 

For a detailed study of the structural properties of LMW and HMW fraction thin films t 10-200 nm) grazing-incidence diffraction techniques [25] have been employed. As mentioned above, P3HT films show mostly lamellae structure with possible edge-on and face-on orientation [21]. The scattering scheme is shown in Figure 10.1. This set-up allows measurement of a momentum trans-... 

As mentioned previously, CTRs arise as a result of the abrupt termination of a crystal lattice, and the diffuse diffracted intensity connects Bragg points in reciprocal space. In this case, the scattering vector is normal to the surface, and as a result, this technique is very sensitive to surface and interface roughness but not to in-plane atomic correlations. Thus, it yields information that is complementary to that obtained by grazing incidence diffraction. The most important feature of CTR is the characteristic decay of the scattered intensity described by Eq. (38). For surfaces that are not perfectly terminated (i.e., rough) the intensity will decay faster than predicted by this equation, and this can be used as a measure of root-mean-square surface roughness. 

Figure 4.1.1 shows schematic representation of grazing incidence diffraction from a horizontal surface. The diffraction condition for two-dimensional crystals lying in the xy plane is that the component of the scattering vector in the horizontal plane, labeled q y (q y = (4jt/A,)sin0i, (where 20i, is the in-plane angle between... 

Vineyard, G.H., Grazing-incidence diffraction and the distorted-wave approximation for the study of surfaces, Phys. Rev. B 26, 4146, 1982... 

Smilgies D-M (2002) Geometry-independent intensity correction factors for grazing incidence diffraction. Rev Sci Inst 73 1706-1710... 

Weygand M, Wetzer B, Pum D, Sleytr UB, Cuvilher N, Kjaer K, Howes PB, Losche M (1999) Bacterial S-layer protein coupling to Lipids X-ray reflectivity and grazing-incidence diffraction studies. 

The change of crystal orientation within different MFI zeolite film structures was followed with the depth-sensitive grazing incidence diffraction technique. The measurements of the adsorbed and grown zeolite films at different incident and exit angles reflect the distribution of the crystal orientation along the film thickness. With increasing zeolite film thickness most of the crystals change their 6-axes orientation from parallel to perpendicular to the sample s surface. 

Grazing incidence diffraction When the coating is from an inorganic material such as bioceramics (eg, hydroxyapatite, tricalcium phosphate, and bioglass) (Dorozhkin, 2012) and metal coating (eg, TiN) (Paschoal et al., 2003), their atomic structural data... 

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