Evaluation of electron threshold energy for predicting radiation damage in transmission electron microscopy

The electron threshold energy (E_t) of a material is a critical parameter for anyone conducting research using transmission electron microscopy (TEM). For studies involving irradiation damage, the electron beam energy must exceed the material's E_t to enable in-situ electron irradiation experiments. In contrast, for researchers focused on microstructural characterization, it is essential to ensure that the beam energy remains below E_t to avoid electron-beam-induced radiation damage, which could compromise the accuracy and reliability of the TEM analysis. This study revisits the commonly used formula for calculating E_t, originally cited in the textbook by Williams and Carter, and identifies significant discrepancies when compared with experimental observations and the original formulation. A corrected formula is proposed and applied to compute E_t values for 81 elements using their minimum displacement energies (E_{d min}). The results are presented in a periodic-table-based diagram, providing practical reference for selecting appropriate TEM accelerating voltages to either induce or avoid irradiation damage.