optical potential

A potential to which the imaginary part is added to incorporate the effect of absorption of an incident beam in a specimen. In the explanation of a TEM image using the dynamical theory, the optical potential is used. The absorption effect which gives the imaginary part of the potential includes plasmon excitation, thermal diffuse scattering and single-electron excitation. Plasmon excitation contributes to the average (normal) absorption and thermal diffuse scattering to the anomalous absorption. Single-electron excitation gives little effect to the anomalous absorption comparing to thermal diffuse scattering.