(i) It is produced when electrons are dislodged from the innermost orbits of the atoms of the target material followed by electron jumps from outer orbits.
(ii) It consists of discrete spectral lines which constitute K-series, L-series and M-series etc. K-series consists of those lines for which electron jumps end at K-level.
(iii) K-series being most energetic constitute the hard X-rays where as L- and M-series form the ‘soft’ X-rays.
(iv) Line spectrum is characteristic of the target material used. In fact, X-rays constituting the line spectrum are known as characteristic X-rays. The number of lines present in the spectrum depends both on the nature of target material and the excitation voltage.
(v) There is a regular shift towards shorter wavelength in the K spectrum as the atomic number of the target is increased figure. The exact relationship, as found by Moseley, is
where v1 is the frequency of the Kα line for a target material having an atomic number of Z1 and v2 and Z2 are similar quantities for some different target material.
