MEAN DEPTH OF X-RAY-PRODUCTION BY ELECTRON-BEAMS IN THICK TARGETS

An analytical expression was deduced for calculating the mean depth of ionization, pz, in electron probe x‐ray microanalysis. The data used were generated from previous Monte Carlo calculations for bulk targets of aluminium, titanium, iron, copper, arsenic, indium, tungsten, gold and lead at normal electron incidence for energies ranging from 10 to 40 keV. The results show that the mean depth pz depends on the back scattering coefficient,η, the energy of the incident electron, Eo, the excitation energy of the target atoms, Ec, and the target atomic number, Z. In the case of non‐normal incidence, it is found that the ratio of the mean depth pz(α) at an angle of incidence α to the mean depth pz(0) at normal incidence varies linearly with cos α and depends only on the atomic number of the target material. The effect of the atomic number of the target on the ionization mean depth was also studied. Copyright © 1990 John Wiley & Sons Ltd.