....is/are type of x-ray tables:
- a- fixed table
- b- moving table
- c- tilting table
- d- All of the above.
characteristic X-rays:
The characteristic X-rays are emitted by heavy elements, when their electrons make transitions between the lowest levels of atomic energy. The characteristic X-ray emission, shown in the illustration on the left as two sharp peaks, occurs when vacancies occur in the n = 1 or K layer of the atom and electrons fall from above to fill the gaps. X-rays produced by transitions from levels n = 2 to n = 1 are called K-alpha X-rays and those corresponding to the transition of n = 3 → 1 are called K-beta X-rays.
The transitions an = 2 or layer L are designated as XL rays (n = 3 → 2 is L-alpha, n = 4 → 2 is L-beta, etc.) The continuous distribution of X-rays that forms the basis for the two Sharp peaks on the left is called "braking radiation."
X-ray production:
X-ray production typically involves the bombardment of a metal target in an X-ray tube, with high-speed electrons that have been accelerated by tens or hundreds of kilovolts of potential. The bombing electrons, can eject electrons from the inner layers of the metal target atoms. These vacancies are quickly filled by electrons that fall from the upper levels, emitting X-rays with well-defined frequencies, associated with the difference between the atomic energy levels of the target atoms.
frequencies of X-rays:
The frequencies of the characteristic X-rays can be predicted from the Bohr model. Moseley measured the frequencies of the characteristic X-rays, of a large fraction of elements of the periodic table, and produced a graph of them that is now called the "Moseley graph."
The characteristic X-rays are used, for the investigation of the crystalline structure by X-ray diffraction. The dimensions of the crystalline network can be determined, with the use of Bragg's law in a Bragg spectrometer.
braking radiation:
"Bremsstrahlung" means "braking radiation", and is retained from the original in German, to describe the radiation that is emitted when electrons are slowed down or "slowed down", when firing at a metallic target. Accelerated charges emit electromagnetic radiation, and when the energy of the bombardment electrons is high enough, that radiation is in the X-ray region of the electromagnetic spectrum. It is characterized by a continuous distribution of radiation, which becomes more intense and moves towards higher frequencies, when the energy of the bombardment electrons is increased. The curves above are from the 1918 data of Ulrey, who bombarded tungsten targets with electrons of four different energies.
extract electrons:
Bombardment electrons can also extract electrons from the inner layers of metal target atoms, and the rapid filling of those vacancies by electrons that fall from higher levels, results in distinctly defined characteristic X-rays.
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