Laue diffraction picture

Knowing the arrangement of atoms in a crystal, it is easy to calculate the intensity of X-ray reflection. More difficult, however, is the problem of calculating the arrangement of atoms in a crystal from an experimentally measured diffraction picture. This problem is the essence of modem X-ray crystal structure analysis for which M. von Laue (1914) and W.L. and W.H. Bragg (1915) were awarded Nobel Prizes. 

In 1895, Rdntgen experimentally discovered "x-rays" and produced the first picture of the bones of the human hand. This was followed by work ty von Laue in 1912 who showed that solid crystals could act as diffraction gratings to form symmetrical patterns of "dots" whose arrangement depended upon how the atoms were arranged in the solid. It was soon... 

Powder XRD shows one-dimensional patterns created from three-dimensional structures, while SAED patterns are two-dimensional pictures reflecting two-dimensional structural information. The disadvantage of SAED is that the structural information along the projected direction is lost, unless a special technique is used, for example high-order Laue zone (HOLZ) diffraction [14, 15]. The advantage of SAED is that the relation between any two diffraction spots in a pattern, i.e. an interplane angle, can be easily revealed. This helps greatly in determination of a unit cell. 

The Laue techniques used for this purpose can give a picture of the whole changing structure, but the time resolution still restricts it to slow changes (seconds rather than milliseconds). A much faster resolution is obtained from records of single reflections in diffraction patterns of active muscle fibres after electrical stimulation (Huxley Faruqi, 1983). 

The diffraction problem of X-rays in crystals on transmission has been solved by M. Laue. However, a more evident picture has been given by W.L. Bragg and also independently by G.V. Wulf. Formalizing the picture described above, they reduced the scattering of secondary waves to the X-ray reflection from so-called crystallographic planes (see Section 9.1). (These are planes drawn through the nodes of a crystal lattice.)... 

---