(Top left) An absorption contrast image obtained from a secondary-ion battery material, containing O, Mn, Co and Ni elements. The photon energy is 854 eV at the Ni L-edge. (Top: Ni, Mn, O images) Ni, Mn and O fluorescence images obtained from the sample with 854 eV photons, showing the distribution of Ni, Mn and O elements. Scale bar: 1 µm. (Bottom left) Fluorescence spectra obtained at a photon energy below and at the Ni L-edge, 854 and 848 eV, respectively. O, Co, Mn elements are observed with 848 eV photons. With 854 eV photons, strong Ni fluorescence is observed. (Bottom right) Mn L-edge spectra obtained by measuring the Mn fluorescence yield as a function of incident photon energy. Repeated measurement at the L3-edge region, 835–850 eV photon energy, is plotted (blue data).