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A single layer of bismuth deposited on the Cu(100) surface forms long range ordered structural phases at various Bi density. A highly ordered c(2×2) reconstruction is accomplished at 0.5 ML, further Bi deposition induces a c(92×2)R45° structure and a subsequent p(10×10) phase related to the formation of regular dislocations arrays. The transition from a c(2×2) superstructure to the c(92×2)R45° phase is accompanied by a sudden decrease in the work function. Photoemission measurements reveal that the Bi induced states close to the Fermi level, associated to the c(2×2) phase, are strongly quenched when the arrays of dislocations are formed, while at higher binding energies, they undergo an energy shift probably due to a confinement effect. The low-energy single particle excitations and the electron dispersion of the Bi induced states of the c(2×2) phase are compared to the electronic states deduced by theoretical band structure obtained by ab initio calculation performed within the embedding method applied to a realistic semi-infinite system. [ABSTRACT FROM AUTHOR]

The search in two-dimensional condensed matter systems of Rashba-type spin-polarized electronic states is aimed by the possibility to control and manipulate the spin orientation. In this Letter, for the first time, we report on the experimental evidence of a Rashba-type spin splitting in the n = 1 image potential state. The image potential state Rashba splitting here measured at the graphene/Ir(111) interface, as confirmed by theoretical considerations, can be detectable to any metal surface with a significant spin-orbit coupling. [ABSTRACT FROM AUTHOR]

Highlights: [•] The interaction of alkali adatoms with metal surfaces is reviewed. [•] The relevance of the spectral properties in the bond formation is discussed. [•] It is shown the role of the surface projected band gap in determining the alkali electronic resonance features. [•] A critical overview of different theoretical models gives an unified picture of the alkali atom - metal surface bond. [Copyright &y& Elsevier]

We investigate the nature of the adatom-surface interaction in the adsorption of alkali atoms on Cu( 111). Our calculation, exploiting the embedding approach in a density functional theory framework, describes an isolated atom on a metallic surface, which is modeled via a one-dimensional modulated potential. The absence of empirical term in the Hamiltonian guaranties a completely ab initio determination of the electronic properties of the system. The role of the projected energy gap in determining lifetime and binding energy of the adatom resonances is evidenced. On the basis of the electronic properties of the adsorbed alkali atoms the covalemVionic nature of the bonding with the surface is analyzed. [ABSTRACT FROM AUTHOR]

Spin polarized de-excitation of a metastable helium atom interacting with metal surfaces is treated within density functional theory. The method is based on a self-consistent calculation of the spin dependent electronic properties of the system, such as the surface density of states and the localized surface states, to compute the transition rate. On the high work function Ag(100) and Ag(111) surfaces, the helium 2s electron is delocalized in the metal and hence the transition rate is weakly spin dependent. The existence of a Shockley surface state in Ag(111) determines a neutralization rate that is about 59% larger than that from Ag(100). On a low work function metal, namely Na(100), the rate is of smaller magnitude than those on silver because the 2s triplet resonance is found to be more occupied. Consequently, emitted electrons can display a strong spin dependence also for a paramagnetic surface. [ABSTRACT FROM AUTHOR]

Single-layer graphene supported on a metal surface has shown remarkable properties relevant for novel electronic and optoelectronic devices. However, the nature of the electronic states derived from unoccupied surface states and quantum well states, lying in the real-space gap between the graphene and the solid surface, has not been explored and exploited yet. Herein, we use ultraviolet nonlinear angle-resolved photoemission spectroscopy to unveil the coexistence at the graphene/Cu(111) interface of a highest occupied Shockley surface state (HOSS) and the two lowest unoccupied surface states (LUSS). The experimental results and electronic structure calculations, based on one-dimensional model potential, indicate that the two unoccupied states originate from the hybridization of an n=1 image potential state with a quantum well state. The hybridized nature of these unoccupied states is benchmarked by a similar experiment done on single-layer graphene grown on copper polycrystalline foil where only the image state survives being the quantum well state at this interface inhibited. [ABSTRACT FROM AUTHOR]

• A photoemission and X-ray adsorption analysis of Co-TPP films on Fe(0 0 1)- p (1 × 1)O. • A commensurate superstructure is found with Co-TPP molecules on Fe(0 0 1)- p (1 × 1)O. • The Co-TPP/substrate interaction is localized on the Co(II) ion. We present a multitechnique investigation of the structural and electronic properties of the prototypical system composed by ultra-thin films of magnetic molecules [Co-tetraphenyl-porphyrins (Co-TPP)] grown on a ferromagnetic substrate [oxygen passivated Fe(0 0 1), namely the Fe(0 0 1)- p (1 × 1)O surface]. Low Energy electron diffraction (LEED) and scanning tunneling microscopy (STM), coupled with first-principles calculations, reveal the formation of a commensurate superstructure at monolayer coverage, made by a square array of flat-lying TPP molecules. UV–photoemission and inverse photoemission spectroscopies (UPS and IPES) are used to investigate their electronic structure. Similar to our previous results on the Zn–TPP growth on Fe(0 0 1)– p (1 × 1)O, the passivation of the metallic surface is able to preserve the photoemission features characteristic of quasi-free molecules, opening the route towards an exploitation of single oxide layers as protective films in organic/inorganic junctions. X-ray photoemission (XPS) and near edge X-ray adsorption fine structure spectroscopies (NEXAFS), are used to reveal the details of the Co–TPP interaction with the substrate. [ABSTRACT FROM AUTHOR]