Powder and single crystal diffraction vary in instrumentation beyond this. A key component of all diffraction is the angle between the incident and diffracted rays. These X-rays are directed at the sample, and the diffracted rays are collected. Typically, this is achieved by comparison of d-spacings with standard reference patterns.Īll diffraction methods are based on generation of X-rays in an X-ray tube. Conversion of the diffraction peaks to d-spacings allows identification of the mineral because each mineral has a set of unique d-spacings. By scanning the sample through a range of 2 θangles, all possible diffraction directions of the lattice should be attained due to the random orientation of the powdered material. These diffracted X-rays are then detected, processed and counted. This law relates the wavelength of electromagnetic radiation to the diffraction angle and the lattice spacing in a crystalline sample. The interaction of the incident rays with the sample produces constructive interference (and a diffracted ray) when conditions satisfy Bragg's Law ( n λ=2 d sin θ). These X-rays are generated by a cathode ray tube, filtered to produce monochromatic radiation, collimated to concentrate, and directed toward the sample. X-ray diffraction is based on constructive interference of monochromatic X-rays and a crystalline sample. X-ray diffraction is now a common technique for the study of crystal structures and atomic spacing. Max von Laue, in 1912, discovered that crystalline substances act as three-dimensional diffraction gratings for X-ray wavelengths similar to the spacing of planes in a crystal lattice.
0 Comments
Leave a Reply. |
Details
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |