An Empirical Formula of Atomic K-Shell Ionization Cross Sections by Electron Impact

An empirical formula is proposed to describe the K-shell
ionization cross sections by electron impact over a wide range of atomic numbers and overvoltages U (the ratio between the electron incident energy and the binding energy of the electrons in the K-shell). The study is based on the analysis of existing experimental data of K-shell ionization cross sections. The expression shows the results in good agreement with the data for Z < 6 atoms as well as for 6 ≤ Z ≤ 79.