The interfacial properties of $MgCl2$ thin films grown on Ti(0001)

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 $MgCl2/Ti(0001)$ 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 $MgCl2$ either at room or at elevated temperatures. A series of high resolution spectra after step by step $MgCl2$ deposition and gradual annealing indicated strong interaction between $MgCl2$ and the substrate while ISS measurements showed that there is no migration of Ti atoms into the deposit layers. Additional quantities of deposited $MgCl2$ grew stoichimetrically on top of the chemically active interface. Annealing at $∼350°C$ caused clustering of the $MgCl2$ multilayer and TPD results showed that they desorbed stoichimetrically at temperatures between 360 and $380°C$⁠. The interfacial $TiClxMgy$ species dissociated by the disruption of the Cl–Mg bonds at temperatures higher than $400°C$ 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 $730°C$⁠. The present results indicate the occurrence of charge transfer at the $Ti/MgCl2$ interface through the Cl ligands and provide valuable information for catalyst design.