FORTH/ICE-HT, P.O. Box 1414, Rion, Patras GR-26504, Greece.
J Chem Phys. 2010 Aug 21;133(7):074701. doi: 10.1063/1.3473933.
Photoelectron spectroscopy with synchrotron radiation (SRPES), temperature programmed desorption (TPD), low energy electron diffraction (LEED), and ion-scattering spectroscopy (ISS) were used in order to study the MgCl(2)/Ti(0001) interface. A clear hexagonal LEED pattern confirmed the presence of a quite large grain of Ti(0001) on the substrate while no new superstructure was formed after deposition of MgCl(2) either at room or at elevated temperatures. A series of high resolution spectra after step by step MgCl(2) deposition and gradual annealing indicated strong interaction between MgCl(2) and the substrate while ISS measurements showed that there is no migration of Ti atoms into the deposit layers. Additional quantities of deposited MgCl(2) grew stoichimetrically on top of the chemically active interface. Annealing at approximately 350 degrees C caused clustering of the MgCl(2) multilayer and TPD results showed that they desorbed stoichimetrically at temperatures between 360 and 380 degrees C. The interfacial TiCl(x)Mg(y) species dissociated by the disruption of the Cl-Mg bonds at temperatures higher than 400 degrees C and metallic Mg evaporated. The Cl atoms remained attached on the Ti surface but they did not form any ordered structure even after annealing at 730 degrees C. The present results indicate the occurrence of charge transfer at the Ti/MgCl(2) interface through the Cl ligands and provide valuable information for catalyst design.
采用同步辐射光电发射谱（SRPES）、程序升温脱附（TPD）、低能电子衍射（LEED）和离子散射谱（ISS）研究了 MgCl2/Ti(0001) 界面。基片上存在较大的 Ti(0001) 单晶的清晰六方 LEED 花样证实了这一点，而在室温或升温条件下沉积 MgCl2 后，没有形成新的超结构。逐步沉积 MgCl2 和逐步退火后的一系列高分辨谱表明 MgCl2 与基片之间存在强烈的相互作用，而 ISS 测量表明 Ti 原子没有进入沉积层。更多的 MgCl2 以化学计量的形式在化学活性界面上生长。在大约 350°C 退火导致 MgCl2 多层的聚集，TPD 结果表明它们在 360-380°C 的温度下以化学计量的方式脱附。界面处的 TiCl(x)Mg(y)物种在高于 400°C 的温度下通过 Cl-Mg 键的断裂而离解，金属 Mg 蒸发。Cl 原子仍然附着在 Ti 表面上，但即使在 730°C 退火后也没有形成任何有序结构。这些结果表明，在 Ti/MgCl2 界面处通过 Cl 配体发生了电荷转移，并为催化剂设计提供了有价值的信息。
