Growth and characterisation of metal alloy and metal oxide surfaces

Optimisation of epitaxial anatase TiO2 thin films grown on LaAlO3(001) -substrates was performed using ultra-high vacuum based pulsed laser deposition -(PLD) and studied by in-situ reflection high-energy electron diffraction (RHEED). In -addition, ex-situ X-ray diffraction (XRD), atomic force microscopy (AFM), and -scanning transmission electron microscopy (STEM) were performed to characterise -the bulk properties of these thin films. The deposited TiO2 thin film is demonstrated -to have anatase phase and bonded directly to the LaAlO3(001) substrate. In a separate -ultra-high vacuum system low-energy electron diffraction (LEED) and scanning -tunnelling microscopy (STM) measurements were performed and a well-ordered twodomain -(1´4) and (4´1) reconstruction of anatase surface was observed. Analysis of -the STM measurements indicates the coexistence of atomic steps of both 2.5 Å and 5.0 -Å, confirming the existence of two TiO2 domains. The atomic resolution STEM -images reveal that the TiO2/LaAlO3 interface to be terminated with LaO layer and that -the anatase-TiO2 reconstruction was found to be stable during the film growth. Low-energy electron diffraction (LEED), scanning tunneling microscopy (STM) -and density functional theory (DFT) calculations have been used to investigate the -atomic and electronic structure of gold deposited (between 0.8 and 1.0 monolayer) on -the Pt(111) face in ultrahigh vacuum at room temperature. The analysis of LEED and -STM measurements indicates two-dimensional growth of the first Au monolayer. -Change of the measured surface lattice constant equal to 2.80 Å after Au adsorption -was not observed. Based on DFT, the distance between the nearest atoms in the case -of bare Pt(111) and Au/Pt(111) surface is equal to 2.83 Å, which gives 1% difference -in comparison with STM values. The first and second interlayer spacing of the clean -Pt(111) surface are expanded by +0.87% and contracted by −0.43%, respectively. The -adsorption energy of the Au atom on the Pt(111) surface is dependent on the adsorption -position, and there is a preference for a hollow fcc site. For the Au/Pt(111) surface, the -top interlayer spacing is expanded by +2.16% with respect to the ideal bulk value. -Changes in the electronic properties of the Au/Pt(111) system below the Fermi level -connected to the interaction of Au atoms with Pt(111) surface are observed. Detailed structural properties of the Pt3Ti(111) surface have been studing with -the use of ab initio density functional theory calculations and scanning tunelling -microscopy measurements. The DFT calculations show that the atoms composition of -the second and third atomic layer have influence upon the top surface of the Pt3T