ABSTRACT
X-rays are produced by electrons being decelerated from an initial high speed by collisions with a target material. Electrons may be produced by thermoionic emission and given a high velocity by the application of an electric field. When an electron qe collides with a target material, it is rapidly decelerated and a photon is emitted. The wavelengths of the photons involved are mainly in the x-ray region of the electromagnetic spectrum. The most rapid decelerations result in the shortest wavelength photons. For other collisions, the electron may lose energy as photons of larger wavelength, and also lose energy to heat by increasing the vibrational internal energy of the target. The result is a continuous spectrum of photon energies with a minimum wavelength dependent upon the kinetic energy of the electrons. Incoming electrons may also ionize the atoms of the target by ejecting bound electrons from within material. Some of these ejected electrons may come from the innermost energy levels which, in solid, can have energies in excess of 100,000 eV. An outer electron can fall into this vacancy and emit a photon in the process. X-rays resulting from filling of K shell vacancies by an electron from the L shell are called Kα x-rays. X-rays from M to K shell transitions are Kβ, and those from N (and higher) to K transitions are Kγ. Similarly, transitions from M to L are Lα, N (and higher) are Lβ. These emissions result in sharp peaks in the overall energy spectrum of emission which are collectively called characteristic radiation.
