Characterization of the resolving power of a double multilayer monochromator in the energy range of 600–900 eV

Two different pairs of x‐ray reflecting multilayer coatings have been tested in a double crystal monochromator configuration. The two pairs consisted of Ni (0.4 nm)–C (1.85 nm) and NiSi (0.4 nm)–C (1.85 nm), both with 225 periods. In order to determine the resolution in the energy range of 600–900 eV, the photoelectron yield of several 3d transition metal compounds was recorded as well as the throughput around the Ni L lines. We found for both pairs a resolving power of 220. Simulations taking into account the angular divergence of the x‐ray beam yield a resolution of 250. The difference with the observed value can be due to the nonhomogeneity of the multilayer coating.