Femtosecond time-resolved X-ray absorption spectroscopy of anatase TiO2 nanoparticles using XFEL

Yuki Obara; Hironori Ito; Terumasa Ito; Naoya Kurahashi; Stephan Thürmer; Hiroki Tanaka; Tetsuo Katayama; Tadashi Togashi; Shigeki Owada; Yo-ichi Yamamoto; Shutaro Karashima; Junichi Nishitani; Makina Yabashi; Toshinori Suzuki; Kazuhiko Misawa

doi:10.1063/1.4989862

Structural Dynamics (Jul 2017)

Femtosecond time-resolved X-ray absorption spectroscopy of anatase TiO2 nanoparticles using XFEL

Yuki Obara,
Hironori Ito,
Terumasa Ito,
Naoya Kurahashi,
Stephan Thürmer,
Hiroki Tanaka,
Tetsuo Katayama,
Tadashi Togashi,
Shigeki Owada,
Yo-ichi Yamamoto,
Shutaro Karashima,
Junichi Nishitani,
Makina Yabashi,
Toshinori Suzuki,
Kazuhiko Misawa

Affiliations

Yuki Obara: Department of Applied Physics, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8588, Japan
Hironori Ito: Interdisciplinary Research Unit in Photon-Nano Science, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8588, Japan
Terumasa Ito: Department of Applied Physics, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8588, Japan
Naoya Kurahashi: Department of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto 606-8502, Japan
Stephan Thürmer: Department of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto 606-8502, Japan
Hiroki Tanaka: Department of Applied Physics, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8588, Japan
Tetsuo Katayama: Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198, Japan
Tadashi Togashi: Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198, Japan
Shigeki Owada: RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan
Yo-ichi Yamamoto: Department of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto 606-8502, Japan
Shutaro Karashima: Department of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto 606-8502, Japan
Junichi Nishitani: Department of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto 606-8502, Japan
Makina Yabashi: RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan
Toshinori Suzuki: Department of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto 606-8502, Japan
Kazuhiko Misawa: Department of Applied Physics, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8588, Japan

DOI: https://doi.org/10.1063/1.4989862
Journal volume & issue: Vol. 4, no. 4
pp. 044033 – 044033-18

Abstract

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The charge-carrier dynamics of anatase TiO2 nanoparticles in an aqueous solution were studied by femtosecond time-resolved X-ray absorption spectroscopy using an X-ray free electron laser in combination with a synchronized ultraviolet femtosecond laser (268 nm). Using an arrival time monitor for the X-ray pulses, we obtained a temporal resolution of 170 fs. The transient X-ray absorption spectra revealed an ultrafast Ti K-edge shift and a subsequent growth of a pre-edge structure. The edge shift occurred in ca. 100 fs and is ascribed to reduction of Ti by localization of generated conduction band electrons into shallow traps of self-trapped polarons or deep traps at penta-coordinate Ti sites. Growth of the pre-edge feature and reduction of the above-edge peak intensity occur with similar time constants of 300–400 fs, which we assign to the structural distortion dynamics near the surface.

Published in Structural Dynamics

ISSN: 2329-7778 (Online)
Publisher: AIP Publishing LLC and ACA
Country of publisher: United States
LCC subjects: Science: Chemistry: Crystallography
Website: http://sd.aip.org

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