MEMS1054_week4_6v3shorter-crystaldiffraction1

What are the implications of braggs law on i geometry

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diffraction from crystals? What are the implications of Bragg’s Law on i) geometry of diffraction? ii) Diffraction experiments and diffraction data (patterns)? How do we interpret diffraction patterns? Powder Diffraction vis-à-vis single crystal diffraction? Diffraction Methods…

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Figure – X-ray Emission from Molybdenum Metal Using 35,000 V Electron Source (Reference (1)) White radiation , the continuous background, refers to the “Bremsstrahlung”, a continuous wavelength spectrum of X-rays with the minimum wavelength (~0.035nm) equal to 35keV. Characteristic radiation results from atomic electron transitions that are of specific energy (wavelength) and characteristic for a given element, e.g different K-alpha wavelengths for X- radiation from Cu and Cr for instance. X-rays are generated by bombardment of a metal (target) or source with high energy electrons. The continuous deceleration of which results in emission of a continuous spectrum of X-rays (Brehmsstrahlung, Figure 16)
Bragg`s Law of X-ray Reflection (after Guy & Hren) 1. X-rays are scattered by periodically arranged atom sheets, leading to diffraction phenomena, including constructive and destructive interference of the scattered X-ray waves. The resulting diffracted beams appear as if the incident X-rays had been“reflected” from planes of atoms that are separated by a distance of d hkl at an angle of incidence Θ . 2. The geometric condition for constructive interference is given by the Bragg Law. It states that constructive interference occurs if the difference in X-ray travel (path) distance between those X- rays scattered by atoms in adjacent planes of the “reflecting”

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• Fall '10
• Wiezorek
• Diffraction, x-ray diffraction, Bragg Law

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