retarding

"Retarding" means the retardation of an electron beam in a TEM. In the optical system of the electron microscope, a certain voltage is applied to an additional electrode, a lens or a specimen stage to lower (retard) the velocity of the electron beam. Retarding of the electron beam improves the energy resolution of EELS spectra. As an attempt for multi-functionality of TEM, a retarding voltage is applied to the specimen stage for the observation of a low-accelerating-voltage TEM image while the accelerating voltage of the TEM itself is kept unchanged. In addition, changing the retarding potential (voltage) enables us to measure the energy distribution of backscattered electrons and to take a reflection diffraction pattern only from elastically scattered electrons.

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