Theories of X-Ray Emission by Charged Particles

The ionization mechanism of X-rays induced by charged particles is of three kinds (1) Coulomb ionization (2) electron capture, and (3) electron Promotion. 

According to direct Coulomb ionization models (vahd for Z -C and 2)) the ionization cross-section for a certain shell becomes maximum when the reduced energy E/ XU) is equal to unity. Here A is the mass of projectile in electron mass unit and U is the average binding energy of the shell. The direct Coulomb ionization phenomenon is described by the following approximations  

This theory (Garcia 1970) is based on the classical energy transfer process wherein a projectile interacts with an iimer-shell electron having a velocity distribution representative of its binding energy. 

Bang and Hansteen (1959) and later Hansteen and Mosebekk (1973) treated the ion-atom collision process in a semiclassical approximation, considering the projectile motion classically and the transition of the inner-shell electron to the continuum quantum mechanically. 

In this approximation, the incident charged particles are treated as plane waves whereas the target electrons are described by hydrogenic wave function. The interaction between the projectile and the electron is treated to first order 

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