Analytical Sciences

Characterization of Gold Oxides Prepared by an Oxygen-dc Glow Discharge from Gold Films Using a Gold Discharge Ring by X-ray Photoelectron Spectroscopy

Morihide HIGO,* Masaru MITSUSHIO,* Toshifumi YOSHIDOME,* and Sadafumi NAKATAKE**

*Department of Chemistry, Biotechnology, and Chemical Engineering, Graduate School of Science and Engineering, Kagoshima University, 1-21-40 Korimoto, Kagoshima 890-0065, Japan
**Kagoshima University Innovation Center, 1-21-40 Korimoto, Kagoshima 890-0065, Japan

Gold oxides (0.1 – 2.0 nm thick) prepared from gold films by an oxygen-dc glow discharge using a gold discharge ring for 0.17 – 30 min at room temperature were characterized by X-ray photoelectron spectroscopy. The oxide thickness increased with increasing discharge time in contrast to the use of an aluminum ring, and thicker oxide films were obtained. The O 1s spectra show four components: I, II, III, and IV. Components I, II, and IV appear during the early formation periods (≤0.5 min). Components I and II are stable and assigned to hydroxyl groups on the surfaces. Component IV changes into component III (gold oxide) after longer discharge times (≥1 min). The gold oxides (2.0 nm thick) decompose after 15 d at room temperature and decompose immediately at temperatures exceeding 117°C. They also decompose under ultraviolet light irradiation (254, 302, and 365 nm) and decompose more rapidly in water vapor at the shorter wavelengths. The thicker nature of the gold oxides is advantageous for their preservation, and they were preserved in their oxidized state for 196 d in anhydrous dodecane in a dark atmosphere.

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