title: Excitation energy dependence for the Li 1s X-ray photoelectron spectra of LiMn2O4.
abstract: The Li 1s XPS (X-ray Photoelectron Spectroscopy) spectra of LiMn2O4, which is one of the major positive-electrode materials in lithium-ion rechargeable batteries, and MnO2 as a reference material, were measured by a laboratory-type XPS spectrometer. The Li 1s peak was not observed in the spectra excited by the Mg Kalpha line (1253.6 eV), because the Li 1s peak overlapped the background of the Mn 3p peak of LiMn2O4. The photoionization cross section of Mn 3p was larger than that of Li 1s for Mg Kalpha excitation. Therefore, the XPS measurement of LiMn2O4 by soft X-ray synchrotron excitation was carried out at beamline BL-7B on NewSUBARU synchrotron facility. Excitation energies of 110, 120, 130, 140, 150 and 151.4 eV were selected. The Li 1s peak was clearly observed in these XPS spectra. In order to investigate the excitation energy dependence, the area ratio of the Li 1s and Mn 3p peaks in the XPS spectra was plotted against the excitation energy. As a result, when the excitation energy was 110 eV, the area ratio had the maximum value.
authors.affiliation: Toray Research Center, Inc., 3-3-7 Sonoyama, Otsu, Shiga 520-8567, Japan.
authors.forename: Junichi
authors.initials: J
authors.lastname: Tsuji
authors.forename: Manabu
authors.initials: M
authors.lastname: Fujita
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Haruyama
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Kanda
authors.forename: Shinji
authors.initials: S
authors.lastname: Matsui
authors.forename: Naoshi
authors.initials: N
authors.lastname: Ozawa
authors.forename: Takeshi
authors.initials: T
authors.lastname: Yao
authors.forename: Kazuo
authors.initials: K
authors.lastname: Taniguchi