Kichinosuke Hirokawa

X-ray photoelectron spectroscopy of manganese—oxygen systems

Abstract The Mn 2p, Mn 3s, Mn 3p, and O 1s spectra of various manganese oxides were studied at room temperature, 200 °C, and 400 °C. The binding energies of

X-ray photoelectron spectroscopy of Co3O4, Fe3O4, Mn3O4, and related compounds

Abstract The metal 2p region spectra of the mixed valence spinels, Co3O4, Fe3O4, Mn3O4, and related compounds were studied. The satellite splittings of Co 2p 3 2 for the octahedrally coordinated cobaltous ions are 6.2 eV and those for the tetrahedrally coordinated ones are about 5.3 eV. The Co 2p spectrum for Co3O4 is considered to be the sum of spectra of magnetic cobaltous ions and low-spin cobaltic ions. In the cases of Fe3O4 and Mn3O4, the oxidation states were not clearly distinguished because both the divalent and trivalent ions of iron and manganese are high-spin.

On the surface chemical reactions of metal and oxide XPS samples at 300–400° at a high vacuum produced by oil diffusion pumps

Abstract Metal and oxide surface reactions formed by heating in the spectrometer at 300–400° at a vacuum of ca. 10 −9 Torr (oil diffusion pumps) were studied. As a result of spectral observations before and after heating, the metals studied were classified into five groups. In the first group, oxide films on the metal surface are easily evaporated because of the high vapour pressure of oxide; in the second, the oxide films are easily reduced in the spectrometer; in the third, the oxide film formed on the metal is reduced but the bulk oxide is not easily reduced; in the fourth, very stable oxide films are formed and the bulk oxide is also stable; and finally in the fifth, the oxide film formed on the metal is apparently reduced, yet the bulk oxide is very stable.

Spectrometric studies of excitation mechanisms on singly-ionized copperemission lines in Grimm-type glow discharge plasmas with helium mixture technique

Abstract Excitation mechanisms of copper ionic emission lines were investigated in Grimm-type discharge plasmas. Addition of He to the Ar or Ne plasma gas was used to study the plasma characteristics. It was concluded that the excitations can be principally attributed to (resonance) charge transfer reactions between Cu atoms and plasma gas species.

Final states after Ni2p photoemission in the nickel-oxygen system

Abstract The Ni2p, Ni3p, Li1s and O1s XPS spectra were measured for single crystal NiO and LixNi1−xO, cleaved and scraped, respectively, in a spectrometer. The cleaved surface had Ni2p 3 2 peaks at 853.9 and 855.8 eV with an intensity ratio of 1:1, where the FWHM of the former was smaller than that of the latter. The intensity ratio decreased with doping of lithium. Although these peaks had previously been ascribed to di- and tri-valent nickel ions in their ground states, we interpret them here as follows. The peaks at 854 and 856 eV correspond to the final states of Ni2 p 3d9 L and Ni2 p 3d10 L 2, where the underline denotes an electron hole. An O2p electron hole in the ground state is necessary to give the latter final state. The doping of lithium increases the density of electron holes and the intensity of the latter final state. The spectral profile of Ni3p did not change with the addition of lithium. The binding energies of Li1s from the particle surface and the bulk were 55.5 and 53.5 eV, respectively. The large shift is associated with surface contamination. The O1s spectrum of the cleaved NiO had two peaks at 529.5 and 531.5 eV with an intensity ratio of 1:0.1. The FWHM of the peaks at 529.5 eV for NiO and Li0.3Ni0.70 were 1.0 and 1.7 eV, respectively. The binding energy of the main peak for LiNiO2 was 528.7 eV.

Quantitative XPS — multiline approach

Abstract The algorithm for quantitative XPS analysis developed some years ago has been extended by a new presentation of the fundamental parameters and by using as many lines as possible from each element under investigation. It now gives the opportunity to reduce the influences of statistical (from measurement) and systematic errors (from fundamental parameters) on quantitative analysis results.

XPS study of oxides formed on the surface of high-purity iron exposed to air

Angle-resolved XPS and micro-XPS have been used for characterizing reaction products consisting of oxide and oxyhydroxide formed on the surface of high-purity iron exposed to air at room temperature for a long time. Angle-resolved measurements of O Is XPS spectra have shown that an oxyhydroxide layer covers a native oxide layer in the nanometric thickness range formed on the iron surface. Moreover, imaging by micro-XPS has indicated that fine reaction products, which are oxyhydroxides, are heterogeneously formed on the iron surface by exposure to air for a long time. Based on these results, it is considered that initial oxidation occurs on the iron surface uniformly, and the fine reaction products nucleate at some areas and grow during further air exposure.

Emission spectroscopic studies of Grimm-type glow discharge plasma with argon-helium gas mixtures

Abstract The effect of argon/helium pressure ratios on the emission intensity of various Ar II lines is investigated for a Grimm-type glow discharge radiation source, operated with Ar-He mixtures. The relative intensities of the Ar II lines are altered significantly by mixing helium with argon. It is found that the population of the Ar + excited states can be redistributed through He-Ar collisional energy transfer. The energy level of the He singlet metastable state ( 1 S 0 ,20.62 eV) is very important for these processes. If the excitation energy of Ar II lines is higher than that of the He singlet metastable, strong quenching of the Ar II line intensity is observed. However, when the excitation energy is slightly lower, some of the Ar II lines are enhanced by adding helium to the argon plasma. Energy exchanges between the Ar + doublet term states and the He singlet metastable are favoured because the total spin remains unchanged before and after the He-Ar collisions. Furthermore, the helium mixing also exerts a great influence on the emission intensities of the elements sputtered from the cathode of the discharge lamp. The enhancement of Al I and Al II emission intensities at suitable Ar-He mixture ratios is discussed for when aluminum is employed as a cathode material.

The effect of the next nearest neighbor ion on the X-ray photoelectron spectra of 2p levels for Co2+, Ni2+ and Cu2+ in MgO

Abstract The X-ray photoelectron spectra of Co, Ni and Cu 2p levels for samples of MxMg1-xO (M = Co, Ni, Cu), CoO, NiO and CuO were compared. The binding energies of metal 2p 3 2 levels did not change with their concentration. The shake-up satellite main peak intensity ratios and FWHM of metal 2p levels for Co2+ and Cu2+ in MgO were smaller than those for CoO and CuO. The Ni 2p 3 2 spectrum for Ni2+ in MgO had no shoulder, unlike NiO. Results indicate that next nearest neighbor ions (metal ions) may influence the final states after photoelectron ejection.

Determination of trace amounts of selenium and tellurium in high-purity iron by electrothermal atomic absorption spectrometry after reductive coprecipitation with palladium using ascorbic acid

Abstract Trace amounts of selenium and tellurium in high-purity iron were quantitatively separated by a reductive coprecipitation technique with palladium, and determined by electrothermal atomic absorption spectrometry. When ascorbic acid was used as reductant, selenium and tellurium could be simultaneously separated from large quantities of iron. The precipitate was dissolved in HNO3 and HCl, then the sample solution was injected into a graphite furnace with ascorbic acid solution. The atomic absorbance of selenium was increased about 4 times, and the atomic absorbance of tellurium was increased about 3.5 times by the presence of palladium. The detection limits (3σ) of selenium and tellurium were 0.017 μg g−1 and 0.011μg g−1, respectively.