X-ray principle
Definition of X-rays
X-rays are particle streams generated by the transition of electrons in atoms between two energy levels with vastly different energies, and are electromagnetic waves with wavelengths between ultraviolet and gamma rays. Its wavelength is very short, ranging from 0.01 to 100 angstroms.
X-rays have high penetration ability and can pass through many materials that are opaque to visible light, such as ink paper, wood, etc. This invisible radiation can cause visible fluorescence in many solid materials, resulting in photographic film sensitivity and air ionization effects.
X-ray principle
The wavelength of X-rays is similar to the spacing between the atomic planes inside the crystal, and the crystal can serve as a spatial diffraction grating for X-rays. When a beam of X-rays is irradiated onto an object, it is scattered by the atoms in the object, and each atom produces a scattered wave. These waves interfere with each other, resulting in diffraction. The superposition of diffraction waves results in an increase in the intensity of the radiation in certain directions and a decrease in other directions.
Characteristic X-rays and their diffraction X-rays are short wavelength electromagnetic waves that can penetrate a certain thickness of material and cause fluorescent substances to emit light, camera latex to sense light, and gas ionization. Using high-energy electron beams to bombard metal targets to generate X-rays, which have specific wavelengths corresponding to the elements in the target, are called characteristic X-rays.
For crystal materials, when the tested crystal is at different angles to the incident beam, those crystal planes that satisfy Bragg diffraction will be detected, which are reflected in the XRD pattern as diffraction peaks with different diffraction intensities. For amorphous materials, because there is no long-range order of atomic arrangement in the crystal structure, but there is short-range order within a few atomic ranges, the XRD spectrum of amorphous materials is some diffuse scattering Mantou peaks.
