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  • 1. Andersson, C B M
    et al.
    Andersen, J N
    Persson, P E S
    Karlsson, Ulf O
    KTH, School of Information and Communication Technology (ICT).
    Bulk and surface electronic structure of InAs(110)1998In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 398, no 3, 395-+ p.Article in journal (Refereed)
    Abstract [en]

    The InAs(110) cleavage surface has been investigated by angle-resolved photoelectron spectroscopy. A separation between the In 4d(5/2) bulk component and the valence band maximum of 16.8 eV is found to be consistent with normal emission spectra. Experimental energy band dispersions, E-i(k), for the four bulk valence bands are established along the Sigma-line of the bulk Brillouin zone. A bulk band structure calculation utilizing the augmented plane-wave method is made. The experimental and calculated E-i(k) dispersions are found to be in good agreement with each other. E-i(k(parallel to)) dispersions for two surface-related structures are established along the lines <(Gamma)over bar>-(M) over bar and (Y) over bar-(M) over bar of the surface Brillouin zone. (C) 1998 Elsevier Science B.V.

  • 2. Andersson, C B M
    et al.
    Karlsson, Ulf O
    KTH, School of Information and Communication Technology (ICT).
    Hakansson, M C
    Olsson, L O
    Ilver, L
    Kanski, J
    Nilsson, P O
    Surface atomic structure of InAs((111)over-bar)2x2 and InSb((111)over-bar)2x2 studied by core level spectroscopy1996In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 347, no 1-2, 199-206 p.Article in journal (Refereed)
    Abstract [en]

    Surface sensitive high resolution core level spectroscopy has been applied to the molecular beam epitaxy grown InAs((111) over bar)2 x 2 and InSb((111) over bar)2 x 2 surfaces. For both systems the In 4d core level consists of one dominating component while the Group V core levels are deconvoluted into four components. This analysis is consistent with a surface model where the topmost layer consists entirely of arsenic or antimony. In this model, Group V atoms form trimers bound to Group V atoms in the first double layer, leaving a single Group V rest atom per unit cell.

  • 3. ANDERSSON, CBM
    et al.
    KARLSSON, Ulf O
    KTH, School of Information and Communication Technology (ICT).
    HAKANSSON, MC
    OLSSON, LO
    ILVER, L
    KANSKI, J
    NILSSON, PO
    PERSSON, PES
    SPUTTERED AND ANNEALED INAS(111)OVER-BAR - AN UNRECONSTRUCTED SURFACE1994In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 307, 885-889 p.Article in journal (Refereed)
    Abstract [en]

    The electronic structure of the InAs(111BAR)1 X 1 surface has been investigated by angle resolved photoelectron spectroscopy along the symmetry lines GAMMAKBAR, GAMMAMBAR, and GAMMAMBAR of the surface Brillouin zone. The bulk valence band structure was calculated using a combination of the linear augmented plane-wave method and the relativistic augmented plane-wave method. We have projected the theoretical bulk band structure onto the surface Brillouin zone to separate surface states from surface resonances. Two surface related structures, S1 and S2, have been observed and their E(i)(k(parallel-to)) dispersions are established. Both S1 and S2 show the symmetry of the 1 X 1 surface Brillouin zone, which is consistent with the observed 1 X 1 LEED pattern. We identify S1 as the As-derived dangling bond state, and S2 is associated with the backbonds connecting the As atoms in the surface layer with the underlying In layer.

  • 4.
    Andrae, Johan C. G.
    et al.
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Johansson, A.
    Björnbom, Pehr
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Rosen, A.
    OH desorption energies for a palladium catalyst characterised by kinetic modelling and laser-induced fluorescence2004In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 563, no 03-jan, 145-158 p.Article in journal (Refereed)
    Abstract [en]

    A kinetic model for the H-2/O-2 reaction on a polycrystalline palladium catalyst has been constructed using CHEMKIN in order to understand the coverage-dependent OH desorption energy. Each adsorbed oxygen atom was modelled to cover four I'd surface sites. The yield of OH and the water production were measured with laser-induced fluorescence (LIF) and microcalorimetry respectively as a function of the relative hydrogen concentration, alpha(H2). The temperature of the catalyst was 1300 K, the total pressure was 13 Pa and the flow was set to 100 SCCM. In fitting the model to the experimental data, the OH desorption energy E-OH(d) was found to have a first-order coverage dependence according to: E-OH(d)(theta) = E-OH(d)(0) - Btheta, where B is a constant set to 92 kJ/mol. The desorption energy at zero coverage E-OH(d)(0) was determined to be 226 kJ/mol. The model could also qualitatively and quantitatively reproduce the apparent desorption energy as a function of alpha(H2); therefore it is believed that the coverage could be predicted by the model. The values for E-OH(d)(theta) were calculated as a function of alpha(H2). From the results of a sensitivity analysis and rate of production calculations' there are strong reasons to believe that the main water-forming reaction on Pd at 1300 K is the hydrogen addition reaction, H + OH reversible arrow H2O. Enthalpy diagrams for the water-forming reactions are also presented.

  • 5. Baudin, M.
    et al.
    Hermansson, Kersti
    KTH, Superseded Departments, Biotechnology.
    Metal oxide surface dynamics from molecular dynamics simulations: the alpha-Al2O3(0001) surface2001In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 474, no 03-jan, 107-113 p.Article in journal (Refereed)
    Abstract [en]

    Constant-stress, constant-temperature (10, 300 and 700 K) molecular dynamics simulations were carried out with shell-model potentials for an infinite crystalline A-terminated alpha -Al2O3(000 1) slab of similar to 25 Angstrom thickness. The surface undergoes considerable relaxation at 10 K, but exhibits ordered surface structures at all three temperatures. The relaxation causes the (0 0 0 1) surface at 10 K to appear oxygen-terminated. The ionic motion within the central and surface regions of the slab system has been analysed in terms of mean-square displacements. At room temperature the (u(2))(surface)/(u(2))(bulk) ratio for the Al ions is approximate to2.5 and when only the out-of-plane surface motion is considered the ratio is as large as approximate to3.5. The O ion motion at the surface is slightly smaller than that of the cations.

  • 6. Baudin, M.
    et al.
    Wojcik, M.
    Hermansson, Kersti
    KTH, Superseded Departments, Biotechnology.
    Dynamics, structure and energetics of the (111), (011) and (001) surfaces of ceria2000In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 468, no 03-jan, 51-61 p.Article in journal (Refereed)
    Abstract [en]

    Molecular dynamics simulations for 20-30 Angstrom thick CeO2 slabs with 2-D periodicity are presented. The three low-index surfaces investigated are(lll), (011) and (001). The simulations were performed within a constant-temperature-constant-pressure ensemble and used the shell-model to describe polarizability. All simulation runs were performed at atmospheric pressure and in the temperature range 10-1100 K. For all three surfaces at both 300 and 1100 K, we find that the surface m.s. displacements are generally larger for the oxide ions than for the cations and that the out-of-plane surface motion is usually larger than the in-plane surface motion. At room temperature, the oxygen m.s. displacements at the (Ill)surface are a factor 1.2 larger than in the bulk, a factor 1.6 for the (011) surface and approximately five times larger at the metastable (001) surface compared to the bulk. The effect of the presence of a surface on the ion dynamics [and on the structure for (011)] persists all the way to the slab centres. even for these rather thick slabs. Our simulations for the polar (001) surface demonstrate that the relative stabilities of different faces and surface terminations can change with temperature, and that it may not always be meaningful to consider one specific user-prepared termination as superior to the others.

  • 7.
    Belonoshko, Anatoly B.
    et al.
    KTH, School of Engineering Sciences (SCI), Theoretical Physics, Condensed Matter Theory.
    Rosengren, Anders
    KTH, School of Engineering Sciences (SCI), Theoretical Physics, Condensed Matter Theory.
    Hultquist, Gunnar
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Corrosion Science.
    Thermal regimes of passivative oxide film formation on Al surface: Theoretical and experimental study2006In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 600, no 20, 4796-4800 p.Article in journal (Refereed)
    Abstract [en]

    We report results of ab initio molecular dynamics simulations of an Al surface exposed to an oxygen atmosphere. The results, supported by experiments performed in this study, demonstrate that the Al surface, by reacting with the oxygen molecules, can be heated above melting temperature and transformed into a liquid. This process is potentially capable of creating an amorphous corrosion scale which might possess an enhanced resistance to deterioration.

  • 8. Bjorkqvist, M
    et al.
    Gothelid, M
    Karlsson, Ulf O
    KTH, School of Information and Communication Technology (ICT).
    Nitride formation and dangling-bond passivation on Si(111)-(7x7) with NH31997In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 394, no 1-3, L155-L161 p.Article in journal (Refereed)
    Abstract [en]

    Thermal nitridation of the Si(111)-(7 x 7) reconstructed surface with ammonia has been investigated using scanning tunneling microscopy (STM). True nitride formation in the form of ring-like structures as in stoichiometric silicon nitride (Si3N4) was observed at imperfections on the surface, which otherwise preserved the characteristics of the (7 x 7) reconstruction. However, the ratio of reacted adatoms in the reconstruction never exceeded similar to 50%, indicative of a frustrated saturation behavior for the adatom dangling bonds in the Si(111)-(7 x 7)-NH3 reaction system. (C) 1997 Elsevier Science B.V.

  • 9.
    Brena, Barbara
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Palmgren, Pål
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Nilson, Katharina
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Yu, Shun
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Hennies, F.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Agnarsson, Björn
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Önsten, Anneli
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Månsson, Martin
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Göthelid, Mats
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    InSb-TiOPc interfaces: Band alignment, ordering and structure dependent HOMO splitting2009In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 603, no 20, 3160-3169 p.Article in journal (Refereed)
    Abstract [en]

    Thin films of titanyl phthalocyanine (TiOPc) have been adsorbed on InSb(1 1 1) (3 x 3) and InSb(1 0 0) c(8 x 2) surfaces and studied with respect to their electronic structure using photoemission (PES), density functional theory (DFT) and scanning tunneling microscopy (STM). The interface chemical interaction is weak in both cases; no adsorbate induced surface band bending is observed and the energy level alignment across the interface is determined by the original position of the substrate Fermi level and the charge neutrality level of the molecule. Room temperature adsorption results in disordered films on both surfaces. The behaviors after annealing are different; on InSb(1 0 0) well-ordered molecular chains form along and on top of the In-rows, whereas on (1 1 1) no long range order is observed. The disorder leads to intermolecular interactions between the titanyl group and neighboring benzene rings leading to a split of TiOPc HOMO (highest occupied molecular orbital) by as much as 0.8 eV.

  • 10. Castleton, Christopher W. M.
    et al.
    Nokbin, Somkiat
    Hermansson, Kersti
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Correlations between magnetic properties and bond formation in Rh-MgO(001)2007In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 601, no 5, 1218-1230 p.Article in journal (Refereed)
    Abstract [en]

    We present the results of first principles calculations for the magnetism of Rh adlayers on MgO(001), at three different adsorption sites and three different coverages, corresponding to 1, 1/2 and 1/8 monolayers. Finite magnetization is found in all cases except that of one Rh monolayer above the oxygen site, which is also the most stable. We examine how the magnetization changes as a function of the Rh-surface distance and relate this to changes in the real-space charge density and in the density of states (DOS) as the Rh adlayer interacts with the surface. We find that increasing either the Rh-Rh interaction strength or the Rh-surface interaction strength leads to reduced magnetization, while increasing the former drives a crossover from localized (atomic) to itinerant magnetism. Neither the magnetic transition itself, nor the localized-to-itinerant magnetism crossover, is found to be directly related to the formation of Rh-surface bonds. From a practical point of view, we predict that magnetism in the Rh-MgO(001) system is most likely to be found experimentally at reduced coverages and at low temperatures.

  • 11. CHAKARIAN, V
    et al.
    SHUH, DK
    YARMOFF, JA
    HAKANSSON, MC
    KARLSSON, Ulf O
    KTH, School of Information and Communication Technology (ICT).
    THE ADSORPTION OF I2 ON SI(111)-7X7 STUDIED BY SOFT-X-RAY PHOTOEMISSION1993In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 296, no 3, 383-392 p.Article in journal (Refereed)
    Abstract [en]

    The adsorption Of I2 on Si(111)-7 x 7 at room temperature is studied with soft X-ray photoelectron spectroscopy. I2 adsorbs dissociatively, forming a mixture of SiI, SiI2 and SiI3 moieties, of which SiI dominates. The Fermi level is pinned near mid-gap, moving slightly towards the conduction band as the I coverage increases. The surface work function increases monotonically with I coverage. The I 4d core-level displays a single chemical state, which decreases in binding energy with increasing coverage. Analysis of the Si 2p core-level spectra shows that the adsorption proceeds first by attachment of I to the dangling bonds of the 7 x 7 unit cell and that, at saturation, 1.57 +/- 0.05 ML of I atoms are adsorbed in 1.10 +/- 0.02 ML of SiI(x) groups. These results indicate that substrate Si-Si bonds are broken by reaction with I2. The total I coverage is limited, however, by the availability Of surface dangling bonds that are required to initiate the dissociation Of I2 molecules.

  • 12. Davila, Maria E.
    et al.
    Avila, Jose
    Asensio, Maria Carmen
    Göthelid, Mats
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Karlsson, Ulf O.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Le Lay, Guy
    Perturbation of Ge(111) and Si(111)root 3 alpha-Sn surfaces by adsorption of dopants2006In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 600, no 16, 3154-3159 p.Article in journal (Refereed)
    Abstract [en]

    We test the response of the root 3 x root 3 alpha reconstructions formed by 1/3 monolayer of tin adatoms on silicon and germanium (111) surfaces upon doping with electrons or holes, using potassium or iodine as probes/perturbers of the initial electronic structures. From detailed synchrotron radiation photoelectron spectroscopy studies we show that doping with either electrons or holes plays a complimentary role on the Si and Ge surfaces and, especially, leads to complete conversion of the Sn 4d two-component spectra into single line shapes. We find that the low binding energy component of the Sn core level for both Si and Ge surfaces corresponds to Sn adatoms with higher electronic charge, than the Sn adatoms that contribute to the core level high binding energy signal. This could be analyzed as Sn adatoms with different valence state.

  • 13.
    Delin, Anna
    et al.
    KTH, Superseded Departments, Materials Science and Engineering.
    Tosatti, E
    Emerging magnetism in platinum nanowires2004In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 566, 262-267 p.Article in journal (Refereed)
    Abstract [en]

    We have investigated infinitely long, monostrand Pt nanowires theoretically, and found that they exhibit Hund's rule magnetism. We find a spin moment of 0.6 mu(B) per atom, at the equilibrium bond length. Its magnetic moment increases with stretching. The origin of the wire magnetism is analyzed and its effect on the conductance through the wire is discussed.

  • 14.
    Elgammal, Karim
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics. KTH, Centres, SeRC - Swedish e-Science Research Centre.
    Hugosson, Håkan W.
    Smith, Anderson D.
    KTH, School of Information and Communication Technology (ICT), Electronics, Integrated devices and circuits. Chalmers Institute of Technology, Sweden.
    Råsander, Mikael
    Bergqvist, Lars
    KTH, School of Engineering Sciences (SCI), Applied Physics. KTH, Centres, SeRC - Swedish e-Science Research Centre.
    Delin, Anna
    KTH, School of Engineering Sciences (SCI), Applied Physics. KTH, Centres, SeRC - Swedish e-Science Research Centre. Uppsala University, Sweden.
    Density functional calculations of graphene-based humidity and carbon dioxide sensors: effect of silica and sapphire substrates2017In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 663, 23-30 p.Article in journal (Refereed)
    Abstract [en]

    We present dispersion-corrected density functional calculations of water and carbon dioxide molecules adsorption on graphene residing on silica and sapphire substrates. The equilibrium positions and bonding distances for the molecules are determined. Water is found to prefer the hollow site in the center of the graphene hexagon, whereas carbon dioxide prefers sites bridging carbon-carbon bonds as well as sites directly on top of carbon atoms. The energy differences between different sites are however minute - typically just a few tenths of a millielectronvolt. Overall, the molecule-graphene bonding distances are found to be in the range 3.1-3.3 (A) over circle. The carbon dioxide binding energy to graphene is found to be almost twice that of the water binding energy (around 0.17 eV compared to around 0.09 eV). The present results compare well with previous calculations, where available. Using charge density differences, we also qualitatively illustrate the effect of the different substrates and molecules on the electronic structure of the graphene sheet.

  • 15.
    Eriksson, Jan Christer
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Rusanov, A. I.
    Additional remarks related with the discussion inaugurated by the article "Incompatibility of the Shuttleworth equation with Hermann's mathematical structure of thermodynamics" by D. J. Bottomley et al. [Surf. Sci. 603 (2009) 97]2010In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 604, no 11-12, 1062-1063 p.Article in journal (Refereed)
    Abstract [en]

    Jan Christer Eriksson and Anatoly I. Rusanov critically analyze a paper titled 'Incompatibility of the Shuttleworth equation with Hermann's mathematical structure of thermodynamics' by D. J. Bottomley and co-researchers. According to him, the problem of double counting that Bottomley and co-researchers supposed to be due to involving pairs of terms of the kind xdy + ydx, is not a true research issue but rather a pedagogical one. Within the formal scheme adopted by Gibbs, this problem is properly dealt with by means of a Gibbs Duhem condition. The critics underline that the incompatibility with the mathematical structure of thermodynamics erroneously claimed by Bottomley and co-researchers would apply not just to solid but to liquid interfaces as well, thus invalidating even the firmly rooted Gibbs surface tension equation.

  • 16.
    Eriksson, Jan Christer
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Rusanov, A. I.
    Comments on the article entitled "Incompatibility of the Shuttleworth equation with Hermann's mathematical structure of thermodynamics" by D.J. Bottomley et al.2009In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 603, no 15, 2348-2349 p.Article in journal (Refereed)
    Abstract [en]

    Jan Christer Eriksson and Anatoly I. Rusanov present their views on the article entitled 'incompatibility of the Shuttleworth equation with Hermann's mathematical structure of thermodynamics'. They derive the the general free energy differential expression for a solid fluid interface to continue their discussions. They also focus on discussing the derivation of the Shuttleworth equation within a thermodynamic framework. A pure solid phase composed of a single component is considered for simplicity that is surrounded by a adsorbing and inert gas at low pressure. They also assume that the symmetry of the solid surface is sufficiently high so as to make the surface two-dimensionally isotropic. They have been able to obtain the relevant Helmholtz energy differential expression for an arbitrarily positioned dividing surface by assuming the excess number of moles of the solid component to always remain the same on the basis of the first equation.

  • 17.
    Eriksson, Jan Christer
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Rusanov, A. I.
    Response to the Reply by D. J. Bottomley et al. to the comments written by J. C. Eriksson and A. I. Rusanov entitled Additional remarks related with the discussion inaugurated by the article Incompatibility of the Shuttleworth equation with Hermann's mathematical structure of thermodynamics by D. J. Bottomley et al. [Surf. Sci. 603 (2009) 97]2010In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 604, no 21-22, 2069-2071 p.Article in journal (Refereed)
  • 18.
    Eriksson, Jan Christer
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Rusanov, Anatoly I.
    Reply to the Comments by E. M. Gutman on the article entitled "Additional remarks related with the discussion ... " by J. C. Eriksson and AI Rusanov [Surf. Sci. 604 (2010) 1062-1063]2011In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 605, no 5-6, 646-647 p.Article in journal (Other academic)
  • 19. Giovanelli, L.
    et al.
    Von Schenck, H.
    Sinner-Hettenbach, M.
    Papageorgiou, N.
    Göthelid, Mats
    KTH, Superseded Departments, Materials Science and Engineering.
    Le Lay, G.
    Synchrotron radiation photoelectron spectroscopy study of Pb-Pc thin films on InSb(100)-(4x2)/c(8x2)2001In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 486, no 02-jan, 55-64 p.Article in journal (Refereed)
    Abstract [en]

    The electronic properties and the thermal stability of a thin film of lead-phthalocyanine deposited on the InSb(100)-(4 x 2)/c(8 x 2) surface were studied by synchrotron radiation core level and valence band photoelectron spectroscopy. The interaction between the overlayer and the substrate was determined by analyzing the photoemission spectra of a thin film and of a single monolayer of adsorbed molecules. Subsequently the monolayer was annealed at increasing temperatures, leading first to a gradual change of the oxidation state of the central lead atom, then to a fragmentation of the macrocycle itself.

  • 20. Girard, R T
    et al.
    Tjernberg, O
    Chiaia, G
    Soderholm, S
    Karlsson, Ulf O
    KTH, School of Information and Communication Technology (ICT).
    Wigren, C
    Nylen, H
    Lindau, I
    Electronic structure of ZnO(0001) studied by angle-resolved photoelectron spectroscopy1997In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 373, no 2-3, 409-417 p.Article in journal (Refereed)
    Abstract [en]

    The electronic structure of the ZnO(0001) surface was studied by angle-resolved photoelectron spectroscopy. The recorded normal emission spectra give information about the Valence band states as well as the Zn 3d states. The dispersions of the four valence bands observed in the (0001) direction were compared with theory and are in good agreement with recent calculations which consider the Zn 3d electrons as part of the valence band. The Zn 3d states are seen to separate into two groups of four and six bands, which show dispersion with k(perpendicular to). This is in agreement with theoretical results but the location of these states were not accurately predicted. The present photoemission results show that they lie around 10.5 eV below E(F). Two surface states were observed on the (0001) surface. One, at 7.5 eV binding energy, was predicted by theory and is interpreted as arising from the ''back-bondings'' of the Zn 4s-O 2p mixed bulk states. The other one at 4.5 eV below E(F), most likely Zn 4p-0 2p derived, was not predicted by theoretical calculations and this is discussed further in the text. (C) 1997 Elsevier Science B.V.

  • 21. GOTHELID, M
    et al.
    GREHK, TM
    HAMMAR, M
    KARLSSON, Ulf O
    KTH, School of Information and Communication Technology (ICT).
    FLODSTROM, SA
    ADSORPTION OF TIN ON THE GE(111)-C(2X8) SURFACE STUDIED WITH SCANNING-TUNNELING-MICROSCOPY AND PHOTOELECTRON-SPECTROSCOPY1995In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 328, no 1-2, 80-94 p.Article in journal (Refereed)
    Abstract [en]

    The growth and epitaxy of Sn on Ge(111) have been investigated using scanning tunneling microscopy (STM), low energy electron diffraction (LEED) and core level photoelectron spectroscopy for coverages ranging from 0.4 monolayers (ML) to above the critical coverage at 1.6 ML. At the lowest coverage a (root 3 X root 3)R30 degrees reconstruction is formed at an annealing temperature of 250-300 degrees C while an annealing above 500 degrees C creates a dimer-adatom-stacking fault (DAS) (7 X 7) structure. In the (7 X 7) structure we argue that Sn occupies both adatom and dimer sites. A previously suggested difference in the (root 3 X root 3)R30 degrees reconstruction at different coverages could not be revealed in our STM images and it seems likely that the structure is the same both at 0.4 and 0.7 ML Sn coverage. We also report the observation of a new superstructure, a (4 X root 7) reconstruction in the submonolayer regime, which appears as a minority structure in disordered regions adjacent to a (5 X 5) DAS structure, Finally in the post-monolayer region a (3 X 2 root 3) structure, surrounded by vast areas of an amorphous tin overlayer, has been imaged by STM. As the coverage was increased, the amorphous layer completely covered the ordered (3 X 2 root 3) phase, which still could be observed in LEED. Additional room temperature deposition of Sn deteriorated the fractional order LEED spots presumably due to indiffusion of Sn from the interface as the critical coverage was surpassed.

  • 22. GOTHELID, M
    et al.
    HAMMAR, M
    TORNEVIK, C
    KARLSSON, Ulf O
    KTH, School of Information and Communication Technology (ICT).
    NILSSON, NG
    FLODSTROM, SA
    SN-INDUCED SURFACE RECONSTRUCTIONS ON THE GE(111) SURFACE STUDIED WITH SCANNING TUNNELING MICROSCOPY1992In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 271, no 3, L357-L361 p.Article in journal (Refereed)
    Abstract [en]

    Scanning tunneling microscopy (STM) has been used to study different Sn induced reconstructions on the Ge(111) surface; namely the (7 x 7), (5 x 5) and (square-root 3 x square-root 3)R30-degrees structures. The first two have been confirmed to be of the dimer adatom stacking fault (DAS) type with adatoms mainly being Sn. The (square-root 3 x square-root 3)R30-degrees superstructure was found at different Sn depositions. At 0.4 monolayer (ML) Sn coverage a homogeneous Sn adatom layer is adsorbed on the (1 x 1) surface in threefold sites directly over second-layer atoms (T4), while at low coverage, 0.1 ML, the top layer is a mixture of Sn and Ge atoms. We also propose the chemical identities of the different atoms seen in the STM images as related to their apparent height.

  • 23. Gothelid, M
    et al.
    LeLay, G
    Wigren, C
    Bjorkqvist, M
    Karlsson, Ulf O
    KTH, School of Information and Communication Technology (ICT).
    Iodine reaction and passivation of the Ge(111) surface1997In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 371, no 2-3, 264-276 p.Article in journal (Refereed)
    Abstract [en]

    The Ge(111)-I surface has been studied at different I coverages ranging from 0.05 hit up to saturation, and different annealing temperatures, using photoelectron spectroscopy (PES) and scanning tunneling microscopy (STM). At saturation the surface is covered with I in the top site and Gel, species in the bridge site, coexisting with small islands/clusters comprising GeI2, giving a total coverage of I in GeIx species of 1.15 ML. The chemically induced shifts in the Ge 3d core level are 0.39 eV per attached I atom. The coverage determined from the I 4d core level is higher than 1.15 ML, which we explain by the presence of I not bound to Ge. Annealing at 200 degrees C decreases the iodine coverage, whereas the I 4d and Ge 3d line profiles are practically unchanged. Further heating desorbs the iodide species and restores the virgin c(2 x 8) structure.

  • 24. Gotte, A.
    et al.
    Hermansson, Kersti
    KTH, Superseded Departments, Biotechnology.
    Baudin, M.
    Molecular dynamics simulations of reduced CeO2: bulk and surfaces2004In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 552, no 03-jan, 273-280 p.Article in journal (Refereed)
    Abstract [en]

    Results from molecular dynamics simulations for bulk and the (0 1 1) surface of reduced and unreduced CeO2 at 300 K are reported. The presence of vacancies in reduced ceria is found to give rise to many different local structural arrangements, and to a significant broadening of the peaks in the pair-distribution function. This broadening is mainly due to the appearance of these new structural arrangements, and it is not due to the increased ionic motions in the reduced systems.

  • 25.
    Grishin, Michael A.
    et al.
    KTH, School of Information and Communication Technology (ICT), Material Physics.
    Månsson, Martin
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Tjernberg, Oscar
    KTH, School of Information and Communication Technology (ICT), Material Physics.
    Karlsson, Henrik S.
    Optillion AB, Stockholm.
    Karlsson, Ulf O.
    KTH, School of Information and Communication Technology (ICT), Material Physics.
    Anisotropy of electron structure at InAs(111) surfaces by laser pump-and-probe photoemission spectroscopy2005In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 574, no 1, 89-94 p.Article in journal (Refereed)
    Abstract [en]

    The electronic structure and the electron dynamics of the clean InAs(111)A 2 x 2 and the InAs(111)B 1 x 1 surfaces have been studied by laser pump-and-probe photoemission spectroscopy. Normally unpopulated electron states above the valence band maximum (VBM) are filled on the InAs(111)A surface due to the conduction band pinning above the Fermi level (E-F). Accompanied by the downward band banding alignment, a charge accumulation layer is confined to the surface region creating a two dimensional electron gas (2DEG). The decay of the photoexcited carriers above the conduction band minimum (CBM) is originated by bulk states affected by the presence of the surface. No occupied states were found on the InAs(111)B 1 x 1 surface. This fact is suggested to be due to the surface stabilisation by the charge removal from the surface into the bulk. The weak photoemission intensity above the VBM on the (111)B surface is attributed to electron states trapped by surface defects. The fast decay of the photoexcited electron states on the (111)A and the (111)B surfaces was found to be tau(111A) less than or equal to 5 ps and tau(111B) less than or equal to 4ps, respectively. We suggest the diffusion of the hot electrons into the bulk is the decay mechanism. (

  • 26.
    Göthelid, Mats
    et al.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Le Lay, G.
    Karlsson, Ulf O.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    An ordered layer of molecular iodine on Ge(100) 2x12004In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 556, no 03-feb, 203-212 p.Article in journal (Refereed)
    Abstract [en]

    Adsorption of iodine on the Ge(1 0 0) (2 x 1) surface has been investigated by core level and valence band photoelectron spectroscopy and scanning tunnelling microscopy. Iodine binds to dimer atom dangling bonds without disrupting the dimers at all coverages. At saturation a c(2 x 2) ordered layer of molecular iodine develops on top of a (2 x 2) ordered structure of atomic iodine binding to asymmetric Ge-dimers. Annealing destroys the molecular character and etches the surface by Ge dimer bond breaking and attachment of additional iodine to these Ge atoms to form GeI2, which desorbs from the surface.

  • 27.
    Göthelid, Mats
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    von Schenck, Henrik
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Weissenrieder, Jonas
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Åkermark, B.
    Tkatchenko, A.
    Galvan, M.
    Adsorption site, core level shifts and charge transfer on the Pd(111)-I(root 3 x root 3) surface2006In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 600, no 15, 3093-3098 p.Article in journal (Refereed)
    Abstract [en]

    We use core level photoelectron spectroscopy and density functional theory (DFT) to investigate the iodine-induced Pd(1 1 1)-I(root 3 x root 3) structure formed at 1/3 NIL coverage. From the calculations we find that iodine adsorbs preferentially in the fcc hollow site. The calculated equilibrium distance is 2.06 angstrom and the adsorption energy is 68 kcal/mol, compared to 2.45 angstrom and 54 kcal/mol in the atop position. The adsorption energy difference between fcc and hcp hollows is 1.7 kcal/mol. Calculated Pd 3d surface core level shift on clean Pd(1 1 1) is 0.30 eV to lower binding energy, in excellent agreement with our experimental findings (0.28-0.29 eV). On the Pd(1 1 1)-I(root 3 x root 3) we find no Pd 3d surface core level shift, neither experimentally nor, theoretically. Calculated charge transfer for the fcc site, determined from the Hirshfeld partitioning method, suggests that the iodine atom remains almost neutral upon adsorption.

  • 28. Hakansson, M C
    et al.
    Johansson, L S O
    Andersson, C B M
    Karlsson, Ulf O
    KTH, School of Information and Communication Technology (ICT).
    Olsson, L O
    Kanski, J
    Ilver, L
    Nilsson, P O
    The electronic structure of In- and As-terminated InAs(001) surfaces1997In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 374, no 1-3, 73-79 p.Article in journal (Refereed)
    Abstract [en]

    The InAs(001) 2 x 4 and 4 x 2 surfaces have been investigated by angle-resolved photoemission. The X(3) and X(5) points were found to be located 6.0 and 2.7 eV below the valence band maximum, respectively, and the dispersion of bulk bands along the Gamma-X direction in the bulk Brillouin zone were well described by a theoretical calculation. From angle-resolved valence band spectra measured along the high symmetry directions [110] and [1(1) over bar0$], three surface induced stares were identified on both the InAs(001)4 x 2 and the InAs(001)2 x 4 surface. (C) 1997 Elsevier Science B.V.

  • 29. HAKANSSON, MC
    et al.
    KARLSSON, Ulf O
    KTH, School of Information and Communication Technology (ICT).
    KANSKI, J
    NILSSON, PO
    KHAZMI, Y
    HRICOVINI, K
    DIMER FORMATION AND ELECTRONIC-STRUCTURE ON THE GE(100)(2X1)-SB SURFACE1992In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 278, no 1-2, L131-L134 p.Article in journal (Refereed)
    Abstract [en]

    Deposition of antimony on Ge(100)2 X 1 results in a well-ordered, highly passivated surface. From a comparison between core-level data and angle-resolved photoemission data, we conclude that the observed 2 x 1 reconstruction is caused by the formation of symmetric Sb-Sb dimers on the Ge surface.

  • 30. Henriksson, Krister O. E.
    et al.
    Vortler, K.
    Dreissigacker, S.
    Nordlund, K.
    Keinonen, J.
    Sticking of atomic hydrogen on the tungsten (001) surface2006In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 600, no 16, 3167-3174 p.Article in journal (Refereed)
    Abstract [en]

    The sticking of hydrogen atoms with kinetic energies in the range 0.003-10 eV on a clean (001) tungsten surface has been investigated using molecular dynamics simulations. The atoms are found to stick to the surface at 0 and 300 K, with a sticking coefficient smaller than 0.6 for kinetic energies higher than 3 meV. The adsorption sites for H on the W(001) surface are also presented. The dominant site is in perfect agreement with the experimentally found bridge site.

  • 31. Herschend, B.
    et al.
    Baudin, M.
    Hermansson, Kersti
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Electronic structure of the CeO2(110) surface oxygen vacancy2005In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 599, no 03-jan, 173-186 p.Article in journal (Refereed)
    Abstract [en]

    The oxygen vacancy formation on the CeO2(110) surface has been studied by ab initio electronic structure calculations. Embedded-cluster calculations with explicit treatment of the electron correlation from Moller-Plesset perturbation theory (MP2) provide an alternative description of the surface O vacancy compared to previously reported periodic density functional theory (DFT) calculations. The electronic structure at the MP2 level shows a complete localization of the excess electrons on the two surface Ce ions neighboring the vacancy, contrary to the delocalized description seen in the periodic DFT calculations for the CeO2(110) surface (but more in line with DFT+U results recently reported for the partially reduced CeO2 bulk and (001)-surface). Our calculations predict a vacancy formation energy (3.1-3.3 eV at the MP2 level including basis set superposition error (BSSE) correction) and a geometric structure in qualitative agreement with the periodic DFT results, where the surface O ion next to the vacancy assumes a bridging position between the reduced Ce ions.

  • 32. Hirschauer, B.
    et al.
    Göthelid, Mats
    KTH, Superseded Departments, Materials Science and Engineering.
    Davila, M.
    Karlsson, U. O.
    Oxidation of Ce on Si(111) studied by high-resolution photoelectron spectroscopy2000In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 464, no 03-feb, 117-122 p.Article in journal (Refereed)
    Abstract [en]

    The Si(lll)-Ce (2x2) surface was studied by photoelectron spectroscopy during oxidation and annealing. Detailed analysis of the Si 2p core-level spectra and the Ce valence band levels shows that Ce is first oxidised and then promotes oxidation of Si at room temperature by improving the oxygen uptake of the surface. Initially, no oxidation of Si can be recorded, but at exposures of 3 L O-2 or more, SiOx and higher silicon oxides are formed. After annealing to 750 degreesC, a temperature that is generally used to oxidise Si, almost all O leaves the surface. At 1045 degreesC, the Si 2p and the Ce valence band spectra of the sample show almost the same shape as for the original Si(lll)-Ce 2x2 surface. This means that oxidation/reduction of the Si(lll)-Ce 2x2 surface is reversible.

  • 33.
    Hosseinpour, Saman
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Forslund, Mattias
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Johnson, C. Magnus
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Pan, Jinshan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Atmospheric corrosion of Cu, Zn, and Cu-Zn alloys protected by self-assembled monolayers of alkanethiols2016In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 648, 170-176 p.Article in journal (Refereed)
    Abstract [en]

    In this article results from earlier studies have been compiled in order to compare the protection efficiency of self-assembled monolayers (SAM) of alkanethiols for copper, zinc, and copper-zinc alloys exposed to accelerated indoor atmospheric corrosion conditions. The results are based on a combination of surface spectroscopy and microscopy techniques. The protection efficiency of investigated SAMs increases with chain length which is attributed to transport hindrance of the corrosion stimulators in the atmospheric environment, water, oxygen and formic acid, towards the copper surface. The transport hindrance is selective and results in different corrosion products on bare and on protected copper. Initially the molecular structure of SAMs on copper is well ordered, but the ordering is reduced with exposure time. Octadecanethiol (ODT), the longest alkanethiol investigated, protects copper significantly better than zinc, which may be attributed to the higher bond strength of Cu-S than of Zn-S. Despite these differences, the corrosion protection efficiency of ODT for the single phase Cu20Zn brass alloy is equally efficient as for copper, but significantly less for the heterogeneous double phase Cu40Zn brass alloy.

  • 34.
    Hugosson, Håkan Wilhelm
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Eriksson, O.
    Jansson, U.
    Abrikosov, I. A.
    Surface segregation of transition metal impurities on the TiC(100) surface2005In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 585, no 02-jan, 101-107 p.Article in journal (Refereed)
    Abstract [en]

    The segregation energies of 3d (Sc-Cu), 4d (Y-Ag) and 5d (La-Au) transition metal impurities on the (10 0) surface of TiC have been obtained using first-principles electronic structure calculations. The results are in agreement with available experimental data and show that the difference in atomic size between the impurity and host species, as well as the difference in surface energies determines if the impurity will segregate towards the surface or not. The results indicate that the difference in size is the dominant factor for the trends in segregation of transition metal impurities towards the (100) surface of TiC.

  • 35.
    Hugosson, Håkan Wilhelm
    et al.
    KTH, Superseded Departments, Materials Science and Engineering.
    Eriksson, O.
    Jansson, U.
    Ruban, Andrei V.
    KTH, Superseded Departments, Materials Science and Engineering.
    Souvatis, P.
    Abrikosov, I. A.
    Surface energies and work functions of the transition metal carbides2004In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 557, no 03-jan, 243-254 p.Article in journal (Refereed)
    Abstract [en]

    We have performed an ab initio study of the surface energies, surface electronic structures and work functions for the (10 0) surface of the, existent and hypothetical, cubic 3d (Sc-Cu), 4d (Zr-Ag) and 5d (La-Au) transition metal carbides. The calculated surface energies have been compared to predictions using a so-called bond-cutting model and a model based on the so-called bonding energies. The absolute values and rough trends of the surface energies are fairly well predicted within the simple bond-cutting model, as compared to fully self-consistent calculations, while both trends and absolute values are well reproduced within the bonding energy model. The electronic structure (densities of states) of the transition metal carbides at the surface and in the bulk have been calculated. The trends are discussed in relation to the behavior of the surface energy and the work function across the series.

  • 36. Janin, E.
    et al.
    von Schenck, H.
    Hellden, S.
    Tjernberg, Oscar
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Karlsson, Ulf O.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Göthelid, Mats
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Corrosive adsorption of Sn on the Pt(110)(1 x 2) surface2002In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 515, no 03-feb, 462-470 p.Article in journal (Refereed)
    Abstract [en]

    Room temperature deposition of Sn on the Pt(110)(1 x 2) surface has been studied by scanning tunnelling microscopy and core level photoelectron spectroscopy. At low coverage Sri is found in three different configurations; as mobile adatoms in the valley of the missing-row reconstruction, as 1D-Pt-Sn-Pt- alloy chains forming local Pt3Sn(110)2 x 2 regions and finally as 3D alloy islands. At higher coverage these islands form a platinum rich alloy film, which is dissolved in the crystal upon annealing to 600 degreesC.

  • 37.
    Janin, Emmanuelle
    et al.
    KTH, Superseded Departments, Physics.
    Ringler, Sandrine
    KTH, Superseded Departments, Physics.
    Weissenrieder, Jonas
    KTH, Superseded Departments, Physics.
    Åkermark, Torbjörn
    KTH, Superseded Departments, Physics.
    Karlsson, Ulf O.
    KTH, Superseded Departments, Physics.
    Göthelid, Mats
    KTH, Superseded Departments, Physics.
    Nordlund, D.
    Ogasawara, H.
    Adsorption and bonding of propene and 2-butenal on Pt(111)2001In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 482, 83-89 p.Article in journal (Refereed)
    Abstract [en]

    The adsorption of propene and 2-butenal on the Pt(1 1 1) surface has been studied by high resolution photoelectron spectroscopy, both in the mono-and multi-layer regime. The results obtained indicate an involvement of both aliphatic and carbonyl groups in the bonding of 2-butenal with the platinum surface in the sub-monolayer regime.

  • 38. JOHANSSON, LI
    et al.
    HAKANSSON, KL
    KARLSSON, Ulf O
    KTH, School of Information and Communication Technology (ICT).
    CHRISTENSEN, AN
    CORE LEVEL PHOTOEMISSION-STUDY OF CR3SI(100)1991In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 251, 101-107 p.Article in journal (Refereed)
    Abstract [en]

    High resolution photoemission studies of the core levels in Cr3Si have been carried out using synchrotron radiation. Investigations were performed both on the clean surface, cleaned in situ by sputter and annealing cycles, and after oxygen exposures. A surface shifted Si 2p component was observed on the annealed surface but no surface shifted component could be identified in the Cr 3p spectrum. The surface shift was extracted using a curve fitting procedure and found to be -0.30(5) eV. The shift expected due to the loss of coordination at the surface is found to be negative but of about half the size of the observed shift. Upon oxygen adsorption at room temperature a chemically shifted Si 2p component appeared already after an exposure of < 1 L, indicating rapid silicon oxidation, while a chemically shifted Cr 3p component could be resolved only after exposures of about 10 L. These findings are presented and discussed.

  • 39. Kadas, K.
    et al.
    Nabi, Z.
    Kwon, S. K.
    Vitos, Levente
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Ahuja, Rajeev
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Johansson, Börje
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Kollar, J.
    Surface relaxation and surface stress of 4d transition metals2006In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 600, no 2, 395-402 p.Article in journal (Refereed)
    Abstract [en]

    Using the density functional theory formulated within the framework of the exact muffin-tin orbitals method, we present a systematic study of the top layer relaxation and surface stress of 4d transition metals. Our calculations predict layer contractions for most surfaces. We also find that the relaxations of the close packed surfaces decrease with increasing atomic number through the 4d series. We propose that the relaxation is mainly due to the reduction of the number of sp electrons in the surface layer relative to bulk. The surface stress is found to be very sensitive to the relaxation and, therefore, an accurate determination of the layer relaxation is necessary for obtaining reliable values for the surface stress. Comparing the top layer relaxations for the close packed surfaces, we see essential deviations between data derived in different ab initio calculations. At the same time, the overall trend for the present surface stress of 4d metals is in reasonable agreement with recent full-potential data.

  • 40. Karlsson, H S
    et al.
    Ghiaia, G
    Karlsson, Ulf O
    KTH, School of Information and Communication Technology (ICT).
    Electron dynamics and accumulation on the InAs(110) surface1998In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 407, no 1-3, L687-L692 p.Article in journal (Refereed)
    Abstract [en]

    Time- and angle-resolved pump-and-probe photoelectron spectroscopy has been used to study the electron dynamics on the InAs(110) surface. Two states, separated by similar to 0.2 eV, can be identified in the conduction band. The time evolution and energy location of these states suggest that they originate from transiently excited levels related to the InAs bulk conduction band. (C) 1998 Elsevier Science B.V. All rights reserved.

  • 41. Karlsson, H S
    et al.
    Viselga, R
    Karlsson, Ulf O
    KTH, School of Information and Communication Technology (ICT).
    Electron accumulation at the InAs(110) cleavage surface1998In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 402, no 1-3, 590-594 p.Article in journal (Refereed)
    Abstract [en]

    The InAs(110) cleavage surface is studied by photoelectron spectroscopy based on an amplified short-pulse titanium:sapphire laser system in both probe-only and pump-and-probe modes. The probe-only spectra show that electrons accumulate in the conduction band at the surface as a function of time after cleavage, while the pump-and-probe spectra show a different response from the excited accumulation layer peak when using s- and p-polarized probe pulses. Moreover, no surface photovoltage is detected when the accumulation layer is optically pumped. (C) 1998 Elsevier Science B.V. All rights reserved.

  • 42.
    KARLSSON, Ulf O
    et al.
    KTH, School of Information and Communication Technology (ICT).
    HANSSON, GV
    FLODSTROM, SA
    ELECTRONIC-STRUCTURE OF THE HCP PHASE OF SILVER-ALUMINUM ALLOYS1983In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 126, no 1-3, 58-65 p.Article in journal (Refereed)
  • 43. Kaya, S.
    et al.
    Baron, M.
    Stacchiola, D.
    Weissenrieder, Jonas
    Fritz Haber Institute.
    Shaikhutdinov, S.
    Todorova, T. K.
    Sierka, M.
    Sauer, J.
    Freund, H. -J
    On the geometrical and electronic structure of an ultra-thin crystalline silica film grown on Mo(112)2007In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 601, no 21, 4849-4861 p.Article in journal (Refereed)
    Abstract [en]

    The atomic structure of a well-ordered silica film grown on a Mo(112) single crystal substrate is discussed in detail using the experimental and theoretical results available to date. New photoelectron spectroscopy results using synchrotron radiation and ultraviolet spectroscopy data are presented. The analysis unambiguously shows that the ultra-thin silica film consists of a two-dimensional network of corner-sharing [SiO4] tetrahedra chemisorbed on the unreconstructed Mo(112) surface. The review also highlights the important role of theoretical calculations in the determination of the atomic structure of the silica films and in interpretation of experimental data.

  • 44. Kaya, S.
    et al.
    Weissenrieder, Jonas
    Fritz Haber Institute.
    Stacchiola, D.
    Todorova, T. K.
    Sierka, M.
    Sauer, J.
    Shaikhutdinov, S.
    Freund, H. -J
    Formation of one-dimensional molybdenum oxide on Mo(112)2008In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 602, no 21, 3338-3342 p.Article in journal (Refereed)
    Abstract [en]

    The atomic structure of a reconstructed Mo(112)-O(2 x 3) surface has been revisited using photoelectron spectroscopy with synchrotron radiation, scanning tunneling microscopy, infrared reflection absorption spectroscopy and density functional theory. In contrast to previous models, the results are rationalized in terms of the formation of one-dimensional, Mo=O terminated molybdenum oxide involving corner sharing distorted [MoO(6)] octahedra on the (1 x 3) reconstructed Mo(112) surface.

  • 45. Kokko, K.
    et al.
    Ropo, M.
    Punkkinen, M. P. J.
    Laukkanen, P.
    Alatalo, M.
    Vitos, Levente
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Kollar, J.
    Johansson, Börje
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Surface core-level shift of Pd at the AgcPd1-c(111) surface: Nonlinear subsurface effects2007In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 601, no 23, 5419-5423 p.Article in journal (Refereed)
    Abstract [en]

    The surface core-level binding-energy shift (SCLS) of Pd at the AgcPd1-c(111) surface is calculated as a function of bulk concentration of the alloy. The equilibrium volume and the surface concentration profile used in the calculations refer to the 0 K case. The SCLSs are evaluated within the Z + 1 approximation. The results are analysed using the mixing enthalpy of the alloy and the bulk and surface chemical potentials. A relation of the SCLS to the bulk concentration is considered. This relation is shown to be mediated by the surface concentration profile which induces the observed nonlinear behaviour. The results are interpreted using a simple model for the alloy electronic structure.

  • 46. Kuzmin, M.
    et al.
    Punkkinen, Marko Patrick John
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Laukkanen, P.
    Perälä, R. E.
    Lang, J. J. K.
    Dahl, J.
    Adell, J.
    Kokko, K.
    Photoemission and density functional theory study of Ge(100): Clean surface and Yb-induced (2x4) reconstruction2013In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 615, 88-96 p.Article in journal (Refereed)
    Abstract [en]

    Clean and metal-adsorbed (100) surfaces of group-IV semiconductors, such as Si and Ge, often exhibit electronically and structurally similar reconstructions. However, the fundamental bulk properties of group-IV materials can have an impact on particular features of such systems, which are related, e.g., to final-state relaxation in photoemission and thus determine their spectral line shape. Here we have studied Yb/Ge(100)(2 x 4) reconstruction as well as clean Ge(100) surface by high-resolution photoelectron spectroscopy and ab initio calculations. An atomic geometry of both surfaces is thoroughly investigated. A detailed analysis of Ge 3d core-level photoemission, atomic origins of surface-shifted components, and final-state screening effects is presented. In particular, it is demonstrated that the core-hole screening plays an essential role in Ge 3d measurements, and that its amount in the complete screening model correlates well with the core-level binding energy of respective Ge atoms in the initial state. The results are discussed in the proper context of related reconstructions on Si(100).

  • 47. Lang, J. J. K.
    et al.
    Laukkanen, P.
    Punkkinen, Marko Patrick John
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Ahola-Tuomi, M.
    Kuzmin, M.
    Tuominen, V.
    Dahl, J.
    Tuominen, M.
    Perala, R. E.
    Schulte, K.
    Adell, J.
    Sadowski, J.
    Kanski, J.
    Guina, M.
    Pessa, M.
    Kokko, K.
    Johansson, Börje
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Vitos, Levente
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Vayrynen, I. J.
    Tin-stabilized (1 x 2) and (1 x 4) reconstructions on GaAs(100) and InAs(100) studied by scanning tunneling microscopy, photoelectron spectroscopy, and ab initio calculations2011In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 605, no 9-10, 883-888 p.Article in journal (Refereed)
    Abstract [en]

    Tin (Sn) induced (1 x 2) reconstructions on GaAs(100) and InAs(100) substrates have been studied by low energy electron diffraction (LEED), photoelectron spectroscopy, scanning tunneling microscopy/spectroscopy (STM/STS) and ab initio calculations. The comparison of measured and calculated STM images and surface core-level shifts shows that these surfaces can be well described with the energetically stable building blocks that consist of Sn-III dimers. Furthermore, a new Sn-induced (1 x 4) reconstruction was found. In this reconstruction the occupied dangling bonds are closer to each other than in the more symmetric (1 x 2) reconstruction, and it is shown that the (1 x 4) reconstruction is stabilized as the adatom size increases.

  • 48. LELAY, G
    et al.
    ARISTOV, VY
    SEEHOFER, L
    BUSLAPS, T
    JOHNSON, RL
    GOTHELID, M
    HAMMAR, M
    KARLSSON, Ulf O
    KTH, School of Information and Communication Technology (ICT).
    FLODSTROM, SA
    FEIDENHANSL, R
    NIELSEN, M
    FINDEISEN, E
    UHRBERG, RIG
    STM AND SYNCHROTRON-RADIATION STUDIES OF PROTOTYPICAL METAL-SEMICONDUCTOR SYSTEMS1994In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 307, 280-294 p.Article in journal (Refereed)
    Abstract [en]

    Since the origin of surface science noble metal/elemental semiconductor couples have been considered as ''prototypical'' systems. After three decades of research their structural and electronic properties remain an intriguing maze despite recent advances made, especially thanks to the development of the near-field microscopies and the ''tensive use of synchrotron radiation in surface crystallography and in high-resolution photoelectron spectroscopy. In the last few years, lead, as a replacement inert metal, has nearly gained the pole position in the display of exotic behaviour. This paper gives a flavour of this mystery story and highlights some puzzling questions.

  • 49.
    Li, Cui
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology. Institute of Chemical and Physical Processes, Italy.
    Monti, Susanna
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology. Institute of Chemistry of Organometallic Compounds, Italy.
    Li, Xin
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Rinkevicius, Zilvinas
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Carravetta, V.
    Theoretical study of para-nitro-aniline adsorption on the Au(111) surface2016In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 649, 124-132 p.Article in journal (Refereed)
    Abstract [en]

    The electronic structure, bonding properties and dynamics of para-nitro-aniline (PNA) adsorbed on the Au(111) surface for a sub-monolayer coverge have been investigated by density-functional theory (DFT) static calculations and quantum molecular dynamics simulations. Four main adsorption geometries have been identified by DFT energy optimization with the gradient corrected PBE functional and accounting for the role of the van del Waals (vdW) interaction. Quantum dynamics calculations starting from the four different structures have been performed at room temperature to estimate the relative stability of the adsorbates and the presence of barriers for their interconversion. Quantum simulations suggest that the most stable adsorption geometry at room temperature is that of PNA with a slightly distorted molecular plane almost parallel to the Au(111) surface. In a second less populated configuration the PNA molecule interacts with the substrate by its NO2 group while the molecular plane is orthogonal to the surface. The N 1s electron photoemission spectrum has been simulated for the identified adsorbate geometries and a measurable variation of the absolute and relative chemical shift for the two nitrogen atoms in comparison with the known values for PNA in gas phase is predicted.

  • 50. Li, H. N.
    et al.
    Wang, X. X.
    He, Sailing
    Ibrahim, K.
    Qian, H. J.
    Su, R.
    Zhong, J.
    Abbas, M. I.
    Hong, C. H.
    Electronic state of C-60 monolayer on Ag(111) before and after Yb intercalation2005In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 586, no 01-3, 65-73 p.Article in journal (Refereed)
12 1 - 50 of 99
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