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Characterization of the Excited State on Methanol/TiO2(110) Interface (cited:2)
Zhi-qiang Wang1, Qun-qing Hao1, Xin-chun Mao1, Chuan-yao Zhou1, Zhi-bo Ma1, Ze-feng Ren2,3, Dong-xu Dai1, Xue-ming Yang1
1.State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Science, Dalian 116023, China;2.nternational Center for Quantum Materials and School of Physics, Peking University, Beijing 100871, China;3.Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
Abstract:
The electronic structure of methanol/TiO2(110) interface has been studied by photoemission spectroscopy. The pronounced resonance which appears at 5.5 eV above the Fermi level in two-photon photoemission spectroscopy (2PPE) is associated with the photocatalyzed dissociation of methanol at vefold coordinated Ti sites (Ti5c) on TiO2(110) surface [Chemical Science 1, 575 (2010)]. To check whether this resonance signal arises from initial or intermediate states, photon energy dependent 2PPE and comparison between one-photon photoemission spectroscopy and 2PPE have been performed. Both results consistently suggest the resonance signal originates from the initially unoccupied intermediate states, i.e., excited states. Dispersion measurements suggest the excited state is localized. Time-resolved studies show the lifetime of the excited state is 24 fs. This work presents comprehensive characterization of the excited states on methanol/TiO2(110) interface, and provides elaborate experimental data for the development of theoretical methods in reproducing the excited states on TiO2 surfaces and interfaces.
Key words:  Titanium dioxide  Excited states  Two-photon photoemission  Time-resolved
FundProject:
甲醇/TiO2(110)界面激发态的表征
王志强1, 郝群庆1, 毛新春1, 周传耀1, 马志博1, 任泽峰2,3, 戴东旭1, 杨学明1
1.中国科学院大连化学物理研究所分子反应动力学国家重点实验室,大连 116023;2.北京大学物理学院量子材料科学中心,北京 100871;3.量子物质科学协同创新中心,北京 100871
摘要:
用光电子能谱的方法研究了甲醇/TiO2(110)界面的电子结构.在激发波长为400 nm的双光子光电子能谱(2PPE)中,探测到了一个末态能量在费米能级以上5.5 eV的共振信号.之前的研究[Chem. Sci. 1, 575 (2010)]表明,这个共振信号与甲醇在5配位的钛离子(Ti5c)上的光催化解离相关.双光子光电子能谱同时携带初态和中间态的信息.为此设计了一个调谐激发光波长的2PPE实验以及一个单光子光电子能谱(1PPE)和2PPE对比的实验,结果一致表明这个共振信号来自于未占据的中间态,也就是激发态.能带色散关系测量表明这个激发态是局域的.时间分辨2PPE测得这个激发态的寿命是24 fs.
关键词:  二氧化钛  激发态  双光子光电子能谱  时间分辨
DOI:10.1063/1674-0068/28/cjcp1412212
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