The possible spectral resolution in parallel-recorded electron energy-loss spectroscopy (PEELS) attained with a STEM is nearing the fundamental limit set by the energy spread of its cold field-emission electron gun (approx. 0.25 eV). The stabilities of the power supplies (high voltage and bending magnet current) are the main obstacles to realising this resolution: about 1 ppm must be maintained during the exposure. This paper describes a method that fixes the position of the zero-loss peak so that it is not affected by power supply drift; some examples of energy-loss spectra are included.
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