Conitnous X-rays

The X-ray continues spectrum consists of radiations of all possible wave lengths within a certain range. The characteristic spectra consists of definite wave lengths superimposed on the continuous spectrum. The spectrum lines occur in the form of small groups. To understand difference in their shape you have to go through their origin . ORIGIN:- 1) Sometimes a high velocity electron passes close to the nucleus of an atom within the target of the X-ray tube.During the process the electron experiences a strong Coulomb force of attraction due to the nucleus and is suddenly slowed down, at the same time suffering a deflection in its path. During its retardation the electron emits a pulse of e.m. radiation of energy hf. Since the electron suffers all sorts of collisions the retardation suffered is also different. Hence the energy of the emitted X-rays also vary . Hence the X-ray spectra shows all possible wavelengths within a certain range . This gives rise to a continuous spectra (a continuous curve). 2) In some collisions an electron coming with high velocity penetrate through the outer shells of the electrons and strike against an electron in the inner shell, and knockout an electron from the inner shell of the atom . The incident and the dislodged electrons both escape from the atom causing a vacancy in the innermost K shell. An electron from the outer shell (say L shell) in higher energy state jump to the K shell to fill the vacancy . This gives rise to an X-ray photon of energy hf. This causes a vacancy in the L shell , which is again filled up by another electron jumping from one of the outer shells along with the emission of another X-ray photon of different energy.. This process continues till the outer-most shell is reached, thus resulting in the emission of a series of characteristic X- ray photons. This gives rise to sharp lines or peaks superimposed on the continuous line.