Bragg studies

X-ray structural studies have played a major role in transforming chemistry from a descriptive science at the beginning of the twentieth century to one in which the properties of novel compounds can be predicted on theoretical grounds. When W.L. Bragg solved the very first crystal structure, that of rock salt, NaCl, the results completely changed prevalent concepts of bonding forces in ionic compounds. 

Bornite, determination by x-ray emission spectrography, 207, 208 Boundary layers in gases, studied by x-ray absorptiometry, 84 Bragg reflection, 22, 115-124 from a curved crystal, 118-124 from a flat crystal, 115-118 order of, 23... 

X-rays. This was followed by the mathematical solution of crystal structure from X-ray diffraction data in 1913 by Bragg. Since that, many applications of X-ray were foimd including structure determination of fine-grained materials, like soils and days, which had been previously thought to be amorphous. Since then, crystals structures of the day minerals were well studied (Ray and Okamoto, 2003). 

Several methods based on the utilization of x-rays are nsed to study LB fihn structure. Diffractometry and reflectometry are the nsnal ones. Diffractometry is nsed mainly when well-ordered periodic strnctnre is under the investigation and several Bragg reflections are in the x-ray pattern. The position of these reflections is determined by the Bragg eqnation ... 

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. 

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