Fumihiro Honda

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.

X-ray photoelectron spectroscopic observation of nitrogen-containing gases adsorbed at high pressures on some transition metals

Abstract The chemisorbed species formed by reaction of nitrogen-containing gases (NO, N 2 O, N 2 and dry air) on some transition metals (Ni, Cu, Ti, Co and Pd) at high pressures (1–200 torr) are examined by XPS. At least four adsorption species are observed on the surface at ambient temperature. They can be assigned to −NO 3 (407.3 eV), −NO 2 (404.5 eV), −NO (400.0 eV) and the nitrogen bound directly to metal, which shows a characteristic energy value for each metal. This feature differs from the reported results of low pressure adsorption experiments. Relative abundances among the chemisorbed species vary with individual metals and gases.

A photoelectron spectroscopic observation of iron surfaces exposed to N2, N2O, NO, NO2 and air at 200 torr or 1 atm

Abstract Photoelectron spectra from core levels are presented for adsorption of nitrogen-containing gases at 200 torr or 1 atm on iron surfaces. Assignments of each band and the adsorption process are discussed. On the substrate at normal temperature, each gas forms nitride and nitrogen oxide groups (NO, NO 2 and NO 3 ) which appear at 398.6, 400.0, 404.5 and 407.1 eV, respectively. The relative intensifies of each species depend on the gases adsorbed. NO and NO 2 are considered to dissociate on the surface and the oxygen atom adsorb preferentially. The oxygen on the surface can be considered to contribute to the formation of each surface ligand.

On the chemical states of nitrogen on iron surfaces reacted with ammonia and sodium cyanide, studied by X-ray photoelectron spectroscopy

Abstract The reaction products of iron reacted with ammonia gas and molten sodium cyanide are studied using X-ray photoelectron spectroscopy. Ammonia gas dissociates on iron surfaces to form a nitride and a loosely bound NH 3 -like species with N 1 s B.E. s at 397.2 and 399.8 eV, respectively. On iron specimens dipped into molten NaCN three species are found at 398.6, 397.8 and 397.2 eV. The 398.6-eV peak is ascribed to adsorbed −CN, and the 397.8-eV peak to carbonitride formed by the reaction of the cyanide with iron. Decreasing binding energies are found for adsorbed −CN ligand, carbonitride compound and nitride, which seem to correspond to an apparent order of stronger interaction of nitrogen with iron. An iron sample was scratched with a file and the surface species of nitrogen were observed below 400°C. The nitrogen atoms in the sample diffuse and concentrate on the surface, depending on the nitrogen content in the bulk. Desorption patterns of nitrogen from a heated iron surface are examined with a view to the determination of gaseous constituents in metal samples.

Application examples of calculated photoionization cross sections and mean free paths to the quantitative surface analysis by X-ray photoelectron spectroscopy

ZusammenfassungDie berechneten Werte wurden mit den experimentell erhaltenen verglichen und als Anwendungsbeispiel die Oberflächenanalyse von Ag-Au-, Au-Cu- und Cu-Ni-Legierungen diskutiert.SummaryPhotoionization cross sections and mean free paths are calculated and compared with the experimentally obtained values. As an example of application the surface analysis of Ag-Au, Au-Cu and Cu-Ni alloys is discussed.

Desorption of oxygen and nitrogen from iron surfaces Application of X-ray photoelectron spectroscopy to surface analysis.

The patterns of desorption of oxygen and nitrogen from metal surfaces were examined and applied in the determination of gaseous elements in metal samples. The abundance of gaseous elements on metal surfaces is controlled by thermal desorption and diffusion to or from the surface. A heat treatment suitable for the separation of adsorbed gases from those in the bulk sample is discussed. Preheating of the metal samples at ca. 300 degrees in a vacuum reduces the residual adsorbates to a minimum and retards the diffusion of the gaseous elements from the bulk to the surface.