The improvement of spectral resolution brought about by the use of multilayer grating (MG) instead of multilayer mirror (MM) is analyzed. The spectrum of a complex sample containing various elements excited under electron irradiation is studied. This sample is a pellet made by pressing powders of Cu and compounds with Fe and F atoms. The MM is a Mo/B_4C periodic multilayer with a period of about 6 nm; for the MG a grating of 1 μm period has been etched in the MM. It is shown that the MG can easily resolve the F Ka and Fe Lα emissions, separated by about 30 eV, whereas the MM is unable to give such a performance. A comparison with an EDS (SDD) detector is also given. It is also shown that the MG can improve the detection limit. Finally the role of the slit placed in front of the detector is discussed.
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