![]() The angular range of the diffractometer usually restricts n to be 1. Where d is the spacing between Bragg planes, is the incident angle, is the wavelength, and the integer n is the order of the scattered beam, e.g., higher number of n corresponds to bright spot further away from the incident direction. The formula for such constructive interference is : At certain incident angles to the crystal planes (Bragg planes) the scattered beams add together constructively to form bright.The un-scattered incident waves appear as a bright spot (black in a photographic plate) at the center (Figure 13-04a). The oscillations in term re-emit radiation in all directions in the form of spherical waves. Each dipole oscillates under the influence of the electromagnetic waves. The atoms become polarized into dipoles.X-ray is used because its wavelength is in the same order of magnitude of the inter-atomic distance. Incident X-ray is collimated into plane wave and hits the crystal either in one piece or in powdery form.The following provides a brief explanation for the process. ![]() Now widely used in molecular biology and biochemistry as well. ![]() The method isįigure 13-04a X-ray Diffraction They took the diffraction pattern resulting from the interaction between the atoms (in the crystal) and X-ray and developed a formula to find out the inter-atomic distance. The Bragg (father and son) pioneered the discovery to discern the structure of crystals in early 20 th century. ![]()
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