Boersch effect

The Boersch effect is a phenomenon in which the energy spread of the electrons increases as the current of the electrons emitted from the electron gun increases, due to Coulomb interactions between the electrons. As the energy spread increases, the chromatic aberration of the electron lens increases. As a result, the spread of the electron beam in the direction perpendicular to the traveling direction of the electron beam increases and the spatial resolution of the electron microscope image is decreased. The time resolution of the electron microscope image is also decreased because the spread of the electron beam in the traveling direction also increases (in the case of time-resolved TEM using pulsed electrons).

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