X-rays were detected by VKX-ray in 1895 and called X-rays. Over the next two years, the scientist was engaged in their research. During this period, the first X-ray tubes were created. They are the most common source of radiation.
It was found that hard X-rays can penetrate through different materials, as well as soft human tissues. The latter fact quickly found application in medicine.
The discovery of x-rays attracted the attention of scientists of the whole world at that time. In the next year after their discovery, a huge number of works on their study and use were published.
Many scientists have studied the properties of x-rays.
J.Stokes predicted their electromagnetic nature, which was confirmed experimentally by Charles Barclay, who also discovered polarization. German physicists Knipping, Friedrich, Laue detected diffraction (phenomena associated with a deviation from rectilinear propagation). In 1913, independently of each other, Bragg and Wulf discovered a simple relationship between the wavelength, the diffraction angle, and the distance between the nearby atomic planes on the crystal. All of the above work was the basis of structural X-ray analysis. The use of spectra for elemental material analysis began in the 1920s. In the development of the study and application of radiation, a major role belongs to the Physico-Technical Institute, which was founded by AF Ioffe.
The most common source of raysis an X-ray tube. However, the sources may be individual radioactive isotopes. In this case, some directly emit x-rays, while in others, nuclear radiation (a-particles or electrons) bombard the radiation-emitting metal target. The tube has a much higher intensity of radiation than isotope sources. At the same time, the dimensions, cost, and weight of isotope sources are incomparably less than those of a unit with a tube.
Soft X-ray sourcescan be synchrotrons and electronic drives. The intensity of synchrotron radiation is two or three orders of magnitude greater than the radiation of a tube in a certain region of the spectrum.
To the natural sources, which radiate X-rays, include the Sun and other objects in the Cosmos.
In accordance with the mechanism of appearance, the spectra and the radiation itself can be characteristic (ruled) and inhibitory (continuous).
In the second case, by means of the X-ray spectrum, fast particles (charged) are emitted due to their deceleration during interaction with target atoms.
Line radiation is formed as a result ofatomic ionization with the ejection of an electron from one of the shells of an atom. Such a phenomenon can result from the collision of an atom and a fast particle, for example, with an electron (primary x-ray emission), or absorption of a photon by an atom (fluorescent X-ray radiation).
The interaction of rays with matter can createphotoelectric effect, which accompanies their absorption or scattering. This phenomenon is revealed in the case when the first atom ejects one of the internal electrons when the photon is absorbed by the atom. Then either the radiative transition of an atom can occur with the emission of a photon of characteristic radiation, or the ejection of a second electron in a nonradiative transition.
Under the influence of X-rays on crystalsnonmetallic (for example, rock salt) on some sites in the atomic lattice, ions are formed that have a positive additional charge, and close to them there are excess electrons.
