John A. Rotole

Valence band x-ray photoelectron spectroscopic studies to distinguish between oxidized aluminum species

The determination of the detailed chemical nature of oxidized aluminum species is an essential requirement for the study of many important practical aspects associated with aluminum metal and its compounds. While thick oxidized films of aluminum metal can be easily characterized by x-ray powder diffraction when the films are crystalline, thin amorphous films are very difficult to characterize. In this article, a study of the valence band x-ray photoelectron spectrum of aluminum oxides, hydroxides, and oxyhydroxides is reported using monochromatic aluminum Kα X radiation. The valence band spectra obtained are shown to have significant differences for different oxidized aluminum species, and can be well understood by comparison with spectra generated from cluster and band structure calculations. This study compliments earlier published studies from this research group using achromatic radiation, and demonstrates how the use of monochromatic X radiation allows a more conclusive distinction to be made among o...

Gamma-Alumina (γ-Al2O3) by XPS

The XPS spectra of gamma-alumina were collected with a VSW HA150 using monochromatic Al Kα x-radiation. Monochromatic radiation provides a distinct clarity to the peak structure in the valence band of gamma-alumina due to the absence of interfering x-ray satellites from the intense O 2s region. Variations in the intensities and peak separation of the two-peak structure in the valence bands of the oxides, hydroxides, and oxyhydroxides of aluminum allow one to distinguish between these compounds. The valence band, survey, and the Al 2s, Al 2p, O 1s, and C 1s core levels are reported.

Corrundum (α-Al2O3) by XPS

The XPS spectra of corrundum were collected with a VSW HA150 using monochromatic Al Kα x-radiation. Monochromatic radiation provides a distinct clarity to the peak structure in the valence band of corrundrum due to the absence of interfering x-ray satellites from the intense O 2s region. Variations in the intensities and peak separation of the two-peak structure in the valence bands of the oxides, hydroxides, and oxyhydroxides of aluminum allow one to distinguish between these compounds. The valence band, survey, and the Al 2s, Al 2p, O 1s, and C 1s core levels are reported.

Aluminum Phosphate by XPS

The XPS spectra of aluminum phosphate were collected with a VSW HA150 using monochromatic Al Kα x-radiation. Monochromatic radiation provides a distinct clarity to the rich peak structure in the valence band of aluminum phosphate due to the absence of interfering x-ray satellites from the intense O 2s region. The valence band region shows the characteristic phosphate peaks at 13.79 eV and 10.69 eV. The valence band, survey, and the Al 2s, Al 2p, O 1s, and C 1s core levels are reported.

Formation of potentially protective oxide-free phosphate films on titanium characterized by valence band x-ray photoelectron spectroscopy

This paper reports the results of a continuing study focused on preparing novel surface chemistries on metal surfaces. In this paper we report how it is possible to prepare oxide-free titanium metal surfaces protected by a film consisting of phosphate. The surface is prepared by electrochemical treatment in an anaerobic cell which allows electrochemistry to be conducted on samples located in a vacuum system attached to an x-ray photoelectron spectrometer. When a clean metal surface is subjected to electrochemical treatment in aqueous orthophosphoric acid an oxide-free phosphate film can be formed on the metal which is stable on subsequent air exposure. Compositional variations were found with potential and other factors. Identical electrochemical treatment of as-received titanium metal yielded samples that had a surface consisting largely of oxide. The chemical composition of these surface films was studied by core level and valence band x-ray photoelectron spectroscopy. Valence band photoemission interpr...

Oxide-free phosphate films on copper probed by core and valence-band x-ray photoelectron spectroscopic studies in an anaerobic cell

This article reports the results of a study of the formation of phosphate films formed directly on the surface of metallic copper without the presence of an oxide layer. The experiments were performed using aqueous electrochemical treatment in an anaerobic electrochemical cell designed to allow an oxide-free metal surface to be exposed to electrochemical treatment without having to expose the electrode to the atmosphere. The electrochemical treatment was performed using negative voltages (versus a saturated calomel electrode) in 5 M orthophosphoric acid. When the experiments were performed outside the anaerobic cell with as-received metallic copper, the treatment leads to the removal of oxide to leave a metallic surface with negligible amounts of oxide. In the anaerobic cell, however, a film consisting of a mixture of Cu(I) metalphosphate and orthophosphate is formed directly bonded to the metal. When this film is exposed to air for ten days, the surface film, still directly bonded to the metal, is oxidiz...

Boehmite (γ-AlOOH) by XPS

The XPS spectra of Boehmite were collected with a VSW HA150 using monochromatic Al Kα x-radiation. Monochromatic radiation provides a distinct clarity to the peak structure in the valence band of Boehmite due to the absence of interfering x-ray satellites from the intense O 2s region. Variations in the intensities and peak separation of the two-peak structure in the valence bands of the oxides, hydroxides, and oxyhydroxides of aluminum allow one to distinguish between these compounds. The valence band, survey, and the Al 2s, Al 2p, O 1s, and C 1s core levels are reported.

Aluminum Foil by XPS

The XPS spectra of argon ion etched aluminum metal were collected with a VSW HA150. This spectrometer is equipped with monochromatic Al Kα x-radiation, a 16 channel multichannel detector, and an electrostatic hemispherical analyzer with a radius of 150 mm providing an instrument with exceptional capabilities. We report the Al 2p core level with resolved 2p1/2 and 2p3/2 spin-orbit split components. The peak to valley separation on the high binding energy side between the spin orbit components was determined to be 0.18 eV and the separation between these components was 0.44 eV. The valence band, survey, and the Al 2s, O 1s, and C 1s core levels are also reported.

Gibbsite (α-Al(OH)3) by XPS

The XPS spectra of Gibbsite were collected with a VSW HA150 using monochromatic Al Kα x-radiation. Monochromatic radiation provides a distinct clarity to the peak structure in the valence band of Gibbsite due to the absence of interfering x-ray satellites from the intense O 2s region. Variations in the intensities and peak separation of the two-peak structure in the valence bands of the oxides, hydroxides, and oxyhydroxides of aluminum allow one to distinguish between these compounds. The valence band, survey, and the Al 2s, Al 2p, O 1s, and C 1s core levels are reported.

Nordstrandite (Al(OH)3) by XPS

The XPS spectra of Nordstrandite were collected with a VSW HA150 using monochromatic Al Kα x-radiation. Monochromatic radiation provides a distinct clarity to the peak structure in the valence band of Nordstrandite due to the absence of interfering x-ray satellites from the intense O 2s region. Variations in the intensities and peak separation of the two-peak structure in the valence bands of the oxides, hydroxides, and oxyhydroxides of aluminum allow one to distinguish between these compounds. The valence band, survey, and the Al 2s, Al 2p, O 1s, and C 1s core levels are reported.