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Characterization Facilities
Published in Vinod Kumar Khanna, Introductory Nanoelectronics, 2020
When a beam of X-rays interacts with the atoms of a target material, the X-rays undergo scattering. The diffraction of X-rays follows Bragg’s law. The Bragg’s equation is (eq. (2.17)) 2dsinθ=nλ
Diffraction
Published in Myeongkyu Lee, Optics for Materials Scientists, 2019
Here n is an integer. This relation was first derived by W. L. Bragg and is known as the Bragg law or equation. It states that the incident and diffracted beams are coplanar with the normal to the lattice planes and equally inclined to the plane normal. The angle θ (called the Bragg angle) is related to the X-ray wavelength and to the interplanar spacing. A number of planes are involved in scattering because the beam size used for X-ray diffraction is much larger than the interplanar spacing.
Approaching Cancer Therapy with Ruthenium Complexes by Their Interaction with DNA
Published in Ajay Kumar Mishra, Lallan Mishra, Ruthenium Chemistry, 2018
X-Ray crystallography relies on Bragg’s law, which states that X-ray beam reflecting from a surface layer of a crystalline material travels a shorter distance than those reflected by the inner layers. The beams are in-phase if the difference in these distances is an integer value of wavelengths of the incident radiation and hence produces an enhanced signal compared to that out-of-phase. Bragg suggested that the differences in distances relies upon the angle of incidence of the beam so that by changing this angle, a diffraction pattern can be built up which can then be Fourier-transformed and interpreted to give atomic-level structural information. It is extremely attractive to have such data for metal complex–DNA systems, however, it is challenging to crystallize the sample. This is often not a trivial exercise, and always involves carefully chosen short DNA sequences. The biological significance of such structures is not clear. There is also the fact that solid-state crystalline structures do not necessarily bear any relationship to those adopted in biological systems.
Defects characterisation and studies of structural properties of sol–gel synthesised MgFe2O4 nanocrystals through positron annihilation and supportive spectroscopic methods
Published in Philosophical Magazine, 2020
Ann Rose Abraham, B. Raneesh, P. M. G. Nambissan, D. Sanyal, Sabu Thomas, Nandakumar Kalarikkal
Diffraction pattern occurs in accordance with Bragg’s law which connects θ, the angle between the incident radiation and the diffracting plane, with the spacing d(hkl) between the planes and the wavelength λ of the X-ray through the relationThe XRD measurements were done in the range 2θ = 20–80° in steps of 0.02°. The diffraction patterns of the samples are shown in Figure 1. The fundamental diffractions from (311), (400), (511) and (440) planes characterising the cubic spinel structure are in good agreement with the reported data (cubic, space group: Fd¯3 m, ICDD PDF # 88-1943). The reflections from a few other planes (220) and (422) with weak intensities are also observed.
Fluorescent cholesteric liquid crystal polymers with dual properties: design, synthesis and characterisation
Published in Liquid Crystals, 2023
Shuai-Yin Ma, Yuan-Sen Zhi, Hong-Shuang Zhang, Xiao-Zhi He, Bao-Yan Zhang, Fan-Bao Meng, Zhi-Na Ji
X-ray diffraction has become an effective means to study the microstructure of crystal matter and to directly determine the liquid crystal phase as well as its structure. The liquid crystal phase can not only be identified, but also the specific structure and type of the liquid crystal phase can be effectively analysed. Theoretical basis of X-ray diffraction is the famous formula of crystal diffraction – Bragg’s Law: