![]() In its simplest form, Bragg's Law is given by λ = 2 d sin θ where d is the perpendicular distance between the planes contining atoms and θis the glancing angle at which the X-rays fall on the crystal. As Laue patterns are difficult to interpret, Bragg worked out a simple equation that predicts the conditions under which diffracted X-rays beams from a crystal are possible. Max Von Laue found, in 1912 that if X-rays are passed through a crystal they get diffracted. For some time after the discovery of X-rays, there was considerable speculation about the nature of X-rays. In general, therefore, X-ray spectra consist of a continuous spectrum upon which is superposed a line spectrum that is characteristic of the element used as target. The f gives the maximum possible frequency of X-radiation emitted and that corresponds to the short wavelength limit of the emitted spectrum. It is likely that the electron may have lost some of its acquired energy before producing the quantum of radiation. If all this energy is used in producing one quantum of X-radiation, then h f = e V. It is well known that when an electron is accelerated through a potential difference of V it acquires energy e V. ![]() ![]() They are produced when accelerated electrons strike target inside an evacuated tube. Example: X-rays are known to be electromagnetic radiation with wavelength of the order of 1 A ∘. The analysis shows that there will be a strong reflected X-ray beam only if 2 d sin θ = n λ where n is an integer. In certain directions, the interference is constructive and we obtain strong reflected X-rays. These X-rays are diffracted by different atoms and the diffracted rays interfere. These procedures are immediately transferable to the promising technology of multi-energy-dispersive-detector-arrays which are planned to deliver the other breakthrough, that of one-two orders of magnitude improvement in data acquisition rates, that will be needed to realise real-time high-definition colour X-ray diffraction imaging.Suppose, and X-ray bean is incident on a solid, making an angle θ with the planes of the atoms. Here we present a data-collection scenario and reconstruction routine which overcomes the latter barrier and which has been successfully applied to a phantom test object and to real materials systems such as a carbonating cement block. This will impact strongly on many fields of science but there are currently two barriers to this goal: speed of data acquisition (a 2D scan currently takes minutes to hours) and loss of image definition through spatial distortion of the X-ray sampling volume. The ultimate aim of this approach is to realise real-time high-definition colour X-ray diffraction imaging, on the timescales of seconds, so that one will be able to 'look inside' optically opaque apparatus and unravel the space/time-evolution of the materials chemistry taking place. ![]() By analogy to optical imaging, a wide variety of features (structure, composition, orientation, strain) dispersed in X-ray wavelengths can be extracted and colour-coded to aid interpretation. Tomographic Energy-Dispersive Diffraction Imaging (TEDDI) enables a unique non-destructive mapping of the interior of bulk objects, exploiting the full range of X-ray signals (diffraction, fluorescence, scattering, background) recorded. ![]()
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