X-rays were discovered VK Roentgen in 1895 and named the X-rays.Over the next two years, scientists engaged in their research.During this period, we created the first X-ray tubes.They are the most common source of radiation.
It was found that the hard X-rays can penetrate through various materials, as well as soft tissue of a human.The latter fact is quickly found application in medicine.
discovery of X-rays at the time attracted the attention of scientists around the world.The following after their discovery was published a huge amount of work on their study and use.
Many scientists studied the properties of X-rays.J.
. Stokes predicted their electromagnetic nature, which has been confirmed experimentally Charles Barkley, who also opened the polarization.German physicists Knipping, Friedrich Laue diffraction revealed (the phenomena associated with a deviation from the rectilinear propagation).In 1913 independently Bragg Wolfe discovered a simple relation between the wavelength, the diffraction angle and the distance between neighboring atomic planes on the chip.All of the above work formed the basis of X-ray structural analysis.Using the spectra for elemental analysis of the material began in the 20s.In the development of the study and application of radiation play a big role Physico-Technical Institute, which was founded by AF Ioffe.
most common source beam is X-ray tube.However, some sources may be radioactive isotopes.Thus one directly emit X-rays, and at other nuclear radiation (alpha particles or electrons) emitted radiation bombard a metal target.The tube has a much greater intensity of radiation than isotopic sources.At the same time, size, cost, weight from isotopic sources far less than the installation tube.
sources of soft X-rays may be synchrotrons and electronic drives.Synchrotron radiation intensity for two to three orders of magnitude greater emission tube in a certain area of the spectrum.
to natural sources that emit X-rays include the Sun and other objects in space.
In accordance with the mechanism of occurrence of radiation spectra themselves can be characteristic (ruled) and the brake (continuous).
In the second case through the X-ray spectrum emitted by fast particles (charged) due to their inhibition in the process of interaction with the atoms of the target.
line radiation is generated as a result of atomic ionization with the ejection of an electron from one of the shells of the atom.This phenomenon may be a consequence of a collision, and fast atom particles, for example, with an electron (primary X-rays) or photon absorption atom (fluorescent X-rays).
interaction rays with matter can create the photoelectric effect, which accompanies their absorption or scattering.This phenomenon is detected in the case when the acquisition of the atom emits a photon first one of the inner electrons.It may then occur either radiative transition of an atom with the emission of a photon of characteristic radiation or ejection of the second electron in the nonradiative transitions.
Under the influence of X-ray crystal-metallic (eg rock salt) on some nodes in the atomic lattice ions are formed, which have a positive additional charge, and there are close to their excess electrons.
