Calculations of electron shake-off, based on the sudden approximation, have been made for several different processes. In particular, electron shake-off as the result of $\beta$ decay has been computed for each of the shells in 15 different cases from an initial $Z=2\mathrm{} \mathrm{to} 92$. An interpolation of the results has been made for the remaining elements. Calculations were made with nonrelativistic Hartree-Fock wave functions for the lighter elements, and relativistic Hartree-Fock-Slater wave functions for the heavier ones. A comparison is made with available experimental data, and satisfactory agreement is obtained. Other ionization processes amenable to the use of the sudden approximation are also discussed, viz. ${\beta }^{+}$ decay, Auger processes, photo-ionization, internal conversion, electron capture, and inner-shell ionization by electron impact.

• Received 27 December 1967

DOI:https://doi.org/10.1103/PhysRev.169.27