Search

Abstract: An angle-resolved photoemission study of epitaxied Bi(111) film on Si(111)-(7×7) surface has been carried out at a temperature from 10K to 210K. The results show that there exists strong temperature dependence in the valence band of Bi(111) film. The variations in the spectral intensity and shape indicate the importance of phonon-assisted indirect transition in the photoemission process. The thermal sensitivity coefficients and effective Debye temperatures for main spectral peaks are determined from the experimental data. [Copyright &y& Elsevier]

Abstract: Room temperature morphology evolution of Pb thin films, prepared on the Si(111)-7×7 substrate at a low temperature (145K), is investigated by reflection high energy electron diffraction, scanning tunnelling microscopy and angle-resolved photoemission spectroscopy. A critical thickness of 10 monolayers (ML) is identified, below which all the flat films formed at low temperature are unstable against evolution into interconnected islands at room temperature. From 10ML to 21ML, Pb films become stable at room temperature and grow via a bi-layer mode. Above 21ML, the film growth turns into a layer-by-layer mode. A “beating effect” is observed to modulate this special growth mode, which changes the film stability from even (odd) layers to odd (even) layers with a 9ML period. Morphology and electronic structure analysis show that the quantum size effect is responsible for the different morphology evolution behaviour and the magic stability of Pb films. [Copyright &y& Elsevier]

Domain boundaries of superlattices formed on the highly oriented pyrolytic graphite surface are studied by scanning tunneling microscopy. Twist and glide boundaries are identified with help of theoretical simulations. The apparent vertical corrugation difference of the superlattices with the same lattice periodicity is explained in terms of overlayer attenuation. Our study reveals that the intra-layer strain has important effect on the electronic structure of the graphite surface. [Copyright &y& Elsevier]

Highlights • The unusual ClAlPc molecular self-assembled layer on a buffer layer have large deformations compared with the common ClAlPc bilayer. • Almost freestanding environment is provided for the molecules when the influence from the substrate is shielded by the buffer layer. • The dominated intermolecular interaction is likely to be the dispersion forces via Reduced Density Gradient analysis. Abstract We report an unusual self-assembled layer structure of chloroaluminium phthalocyanine (ClAlPc) molecules on highly ordered pyrolytic graphite (HOPG), in which a close-packed well-ordered monolayer is separated from the substrate by a relatively disordered buffer layer, as revealed using scanning tunneling microscopy (STM). Our close-packed monolayer has a nearly rectangular lattice, instead of the distinctly different square lattice for the more commonly observed well-ordered bilayer structure. This may be due to the dominance of intermolecular interactions within the monolayer when the influence from the substrate is shielded by the buffer layer. Density Functional Theory (DFT) calculations and Reduced Density Gradient (RDG) analysis indicate that the dominant intermolecular interaction within the unusual layer is likely the London dispersion force. Graphic abstract Image, graphical abstract [ABSTRACT FROM AUTHOR]

Abstract: The electronic structure of reconstructed surface is measured by angle-resolved photoemission spectroscopy. By the first time, band splitting at and points in the surface Brillouin zone (SBZ) of this system is observed, which could be simply interpreted in the framework of Rashba splitting. Furthermore, first principle calculation is carried out and compared with our experimental results. [Copyright &y& Elsevier]

Abstract: Using angle-resolved photoemission spectroscopy (ARPES), we investigate the electronic structure of Cu-doped topological insulator Bi2Te3 on Si(111) substrate prepared by molecular beam epitaxy (MBE) to clarify the doping nature of Cu atoms in the films. By systematic studying the structural and electronic properties of the Cu-doped Bi2Te3 films by different doping methods, we find that Cu acts as electron donors when deposited onto the surface of Bi2Te3 films while behave as holes when doped in the process of Bi2Te3 thin film growth. The model of the formation of Cu+, five/seven layer lamella structures and Cu2−x Te is proposed to explain the different doping mechanisms. The robustness of topological surface states and insensitivity to non-magnetic impurities is indicated. [Copyright &y& Elsevier]