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The Scherrer equation, in X-ray diffraction and crystallography, is a formula that relates the size of sub-micrometre crystallites in a solid to the broadening of a peak in a diffraction pattern. It is often referred to, incorrectly, as a formula for particle size measurement or analysis.
Rietveld refinement is a technique described by Hugo Rietveld for use in the characterisation of crystalline materials. The neutron and X-ray diffraction of powder samples results in a pattern characterised by reflections (peaks in intensity) at certain positions. The height, width and position of these reflections can be used to determine many ...
Full width at half maximum. In a distribution, full width at half maximum (FWHM) is the difference between the two values of the independent variable at which the dependent variable is equal to half of its maximum value. In other words, it is the width of a spectrum curve measured between those points on the y-axis which are half the maximum ...
The resulting map of the directions of the X-rays far from the sample is called a diffraction pattern. It is different from X-ray crystallography which exploits X-ray diffraction to determine the arrangement of atoms in materials, and also has other components such as ways to map from experimental diffraction measurements to the positions of atoms.
X-ray crystal truncation rod scattering is a powerful method in surface science, based on analysis of surface X-ray diffraction (SXRD) patterns from a crystalline surface. For an infinite crystal , the diffracted pattern is concentrated in Dirac delta function like Bragg peaks .
An X-ray diffraction pattern of a crystallized enzyme. The pattern of spots (reflections) and the relative strength of each spot (intensities) can be used to determine the structure of the enzyme. The relative intensities of the reflections provides information to determine the arrangement of molecules within the crystal in atomic detail.
A variable pathlength cell is a sample holder used for ultraviolet–visible spectroscopy or infrared spectroscopy that has a path length that can be varied to change the absorbance without changing the sample concentration. [1] [2] [3] [4]
There is no theoretical maximum, but in practice, values are considerably less than one even for poor models, provided the model includes a suitable scale factor. Random experimental errors in the data contribute to R {\displaystyle R} even for a perfect model, and these have more leverage when the data are weak or few, such as for a low ...