Investigation of Copper(I) Oxide Quantum Dots by Near-Edge X-ray Absorption Fine Structure Spectroscopy

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• 作者：Ponnusamy Nachimuthu ; Suntharampillai Thevuthasan ; Yong J. Kim ; Alan S. Lea ; Vaithiyalingam Shutthanandan ; Mark H. Engelhard ; Donald R. Baer ; Scott A. Chambers ; David K. Shuh ; Dennis W. Lindle ; Eric M
• 刊名：Chemistry of Materials
• 出版年：2003
• 出版时间：October 7, 2003
• 年：2003
• 卷：15
• 期：20
• 页码：3939 - 3946
• 全文大小：218K
• 年卷期：v.15,no.20(October 7, 2003)
• ISSN：1520-5002

文摘

Copper(I) oxide quantum dots (OQDs) were grown in various thicknesses on differentSrTiO₃(001) surfaces and were investigated by near-edge X-ray absorption fine structure(NEXAFS) spectroscopy. The experimental growth conditions for the OQDs were optimizedto obtain Cu₂O as the major phase. The OQDs grown on clean SrTiO₃(001) surfaces at 825K and higher with p(O₂) of 9.0 × 10^-7 Torr or greater contain mostly CuO, contrasting toOQDs grown at 800 K with p(O₂) of ~7.0 × 10^-7 Torr that contain primarily Cu₂O.Furthermore, there is a strong interaction between the SrTiO₃(001) surface and the firstfew monolayers of the OQDs, which induces the formation of Cu(II). However, this interactionis mitigated with increasing thickness of OQDs, resulting in the exclusive formation of Cu₂Oin the topmost layers. The influence of the SrTiO₃(001) substrate on the formation of OQDscan be minimized by modifying the substrate surface using chemical treatment and/orenergetic Au²⁺ ion-beam irradiation. Examination of the photochemical properties of theseOQDs shows that prolonged soft X-ray irradiation under vacuum reduces Cu(II), which ispresent as a minor impurity in the Cu(I) OQDs.