ELECTRON-ENERGY-LOSS SPECTROSCOPY WITH RESOLUTION BELOW 1 MEV

Presently available electron spectrometers have a theoretical resolution 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 the angular aberrations of the dispersive elements. A new electrostatic dispersive device with controlled angular aberrations is described. An energy loss spectrometer built with such dispersive elements had a theoretical resolution limit of 0.3 meV, and an experimentally achieved resolution of 0.5 meV.