中文摘要：

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400nm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5．5eV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24fs．

英文摘要：

The electronic structure of methanol/TiO2（ll0） interface has been studied by photoemis- sion 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 fivefold coordinated Ti sites （Ti5c） on TiO2 （110） surface [Chem- ical 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 sug- gest 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 char- acterization 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.