title: X-ray-induced reduction of Au ions in an aqueous solution in the presence of support materials and in situ time-resolved XANES measurements.
abstract: Synchrotron X-ray-induced reduction of Au ions in an aqueous solution with or without support materials is reported. To clarify the process of radiation-induced reduction of metal ions in aqueous solutions in the presence of carbon particles as support materials, in situ time-resolved XANES measurements of Au ions were performed under synchrotron X-ray irradiation. XANES spectra were obtained only when hydrophobic carbon particles were added to the precursor solution containing Au ions. Changes in the shape of the XANES spectra indicated a rapid reduction from ionic to metallic Au in the precursor solution owing to synchrotron X-ray irradiation. In addition, the effects of the wettability of the carbon particles on the deposited Au metallic spots were examined. The deposited Au metallic spots were different depending on the relationship of surface charges between metal precursors and support materials. Moreover, a Au film was obtained as a by-product only when hydrophilic carbon particles were added to the precursor solution containing the Au ions.
authors.affiliation: Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Ohkubo
authors.affiliation: Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Nakagawa
authors.affiliation: Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Seino
authors.affiliation: Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors.forename: Junichiro
authors.initials: J
authors.lastname: Kugai
authors.affiliation: Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors.forename: Takao A
authors.initials: TA
authors.lastname: Yamamoto
authors.affiliation: Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki 305-0801, Japan.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Nitani
authors.affiliation: Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki 305-0801, Japan.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Niwa
keywords: Au-LIII edge; X-ray absorption near-edge structure (XANES); radiation-induced reduction; synchrotron X-rays