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Methanol Adsorption on TiO2 Film Studied by Sum Frequency Generation Vibrational Spectroscopy (cited:2)
Ran-ran Feng,An-an Liu,Shuo Liu,Jiao-jian Shi,Yi Liu,Ze-feng Ren*
Author NameAffiliationE-mail
Ran-ran Feng International Center for Quantum Materials (ICQM) and School of Physics, Peking University, Beijing 100871, ChinaCollaborative Innovation Center of Quantum Matter, Beijing 100871, China  
An-an Liu International Center for Quantum Materials (ICQM) and School of Physics, Peking University, Beijing 100871, ChinaCollaborative Innovation Center of Quantum Matter, Beijing 100871, China  
Shuo Liu International Center for Quantum Materials (ICQM) and School of Physics, Peking University, Beijing 100871, ChinaCollaborative Innovation Center of Quantum Matter, Beijing 100871, China  
Jiao-jian Shi International Center for Quantum Materials (ICQM) and School of Physics, Peking University, Beijing 100871, ChinaCollaborative Innovation Center of Quantum Matter, Beijing 100871, China  
Yi Liu International Center for Quantum Materials (ICQM) and School of Physics, Peking University, Beijing 100871, ChinaCollaborative Innovation Center of Quantum Matter, Beijing 100871, China  
Ze-feng Ren* International Center for Quantum Materials (ICQM) and School of Physics, Peking University, Beijing 100871, China zfren@pku.edu.cn 
Abstract:
A broadband infrared surface sum frequency generation vibrational spectroscopy (SFG-VS) and an in situ UV excitation setup devoted to studying surface photocatalysis have been constructed. With a home-made compact high vacuum cell, organic contaminants on TiO2 thin lm surface prepared by RF magnetron sputtering were in situ removed under 266 nm irradiation in 10 kPa O2 atmosphere. We obtained the methanol spectrum in the CH3 stretching vibration region on TiO2 surface with changing the methanol pressure at room temperature. Features of both molecular and dissociative methanol, methoxy, adsorbed on this surface were resolved. The CH3 symmetric stretching vibration frequency and Fermi resonance of molecular methanol is red-shifted by about 6?8 cm-1 from low to high coverage. Moreover, the recombination of dissociative methanol and H on surfaces in vacuum was also observed. Our results suggest two equilibria exist: between molecular methanol in the gas phase and that on surfaces, and between molecular methanol and dissociative methanol on surfaces.
Key words:  Surface sum frequency generation vibrational spectroscopy, Surface photo-catalysis, TiO2
FundProject:
二氧化钛薄膜表面甲醇吸附的和频振动光谱
冯冉冉,刘安安,刘烁,施骄健,刘怡,任泽峰*
摘要:
自行搭建了用于研究表面光催化的宽带红外和频振动光谱并可以原位紫外光激发的装置. 利用自制的结构紧凑小巧的高真空样品池,可以在10 kPa氧气氛围下经原位紫外光照除掉 射频磁控溅射制备的二氧化钛薄膜表面的有机污染物. 通过在室温下改变甲醇气压和指认吸附在薄膜表面的甲醇的和频振动光谱,发现薄膜表面有两种吸附的甲醇,分子形式吸附的甲醇(CH3OH)和解离吸附的甲醇(CH3O). 当甲醇的覆盖度由低变高时,分子形式吸附的甲醇的CH3的对称伸缩振动和费米共振峰红移了6~8 cm-1. 真空下,薄膜表面的甲氧基和表面的氢原子可以重新结合并以甲醇分子的形式脱附. 研究表明二氧化钛薄膜体系存在两个平衡:气相甲醇和表面吸附的甲醇分子之间,以及表面吸附的甲醇分子和甲氧基之间.
关键词:  表面和频振动光谱,表面光催化,二氧化钛
DOI:10.1063/1674-0068/28/cjcp1409154
分类号: