Discovery of deep and shallow trap states from step structures of rutile TiO_2 vicinal surfaces by second harmonic and sum frequency generation spectroscopy

• Takahashi, Hiroaki

• Watanabe, Ryosuke

• Miyauchi, Yoshihiro

• Mizutani, Goro

抄録

In this report, local electronic structures of steps and terraces on rutile TiO_2 single crystal faces were studied by second harmonic and sum frequency generation (SHG/SFG) spectroscopy. We attained selective measurement of the local electronic states of the step bunches formed on the vicinal (17 18 1) and (15 13 0) surfaces using a recently developed step-selective probing technique. The electronic structures of the flat (110)-(1×1) (the terrace face of the vicinal surfaces) and (011)-(2×1) surfaces were also discussed. The SHG/SFG spectra showed that step structures are mainly responsible for the formation of trap states, since significant resonances from the trap states were observed only from the vicinal surfaces. We detected deep hole trap (DHT) states and shallow electron trap (SET) states selectively from the step bunches on the vicinal surfaces. Detailed analysis of the SHG/SFG spectra showed that the DHT and SET states are more likely to be induced at the top edges of the step bunches than on their hillsides. Unlike the SET states, the DHT states were observed only at the step bunches parallel to [1  1] [equivalent to the step bunches formed on the (17 18 1) surface]. Photocatalytic activity for each TiO_2 sample was also measured through methylene blue photodegradation reactions and was found to follow the sequence: (110) < (17 18 1) < (15 13 0) < (011), indicating that steps along [0 0 1] are more reactive than steps along [1 1^-  1]. This result implies that the presence of the DHT states observed from the step bunches parallel to [1  1] did not effectively contribute to the methylene blue photodegradation reactions.

identifier:https://dspace.jaist.ac.jp/dspace/handle/10119/9829

収録刊行物

• Journal of Chemical Physics

  Journal of Chemical Physics 134 (15), 154704-1-154704-13, 2011-04-15

  American Institute of Physics

キーワード

• titanium dioxide
• TiO2
• SHG
• step bunching
• photocatalysis

詳細情報

• CRID: 1050001337538292096
• NII論文ID: 120003184330
• ISSN: 00219606
• Web Site: http://hdl.handle.net/10119/9829
• 本文言語コード: en
• 資料種別: journal article
• データソース種別:
  • IRDB
  • CiNii Articles