ELECTRON-ENERGY-LOSS SPECTROSCOPY WITH RESOLUTION BELOW 1 MEV

Presently available electron spectrometers have a theoretical resoluti on limit of about 1 meV. It is shown that this limitation arises from the combined effect of the angular spread of the space charge limited beam, feeding the energy dispersive elements of the spectrometer and t he angular aberrations of the dispersive elements. A new electrostatic dispersive device with controlled angular aberrations is described. A n energy loss spectrometer built with such dispersive elements had a t heoretical resolution limit of 0.3 meV, and an experimentally achieved resolution of 0.5 meV.