A G Borisov

Publications (88)203.98 Total impact

• Article: Quantum Plasmonics: Nonlocal effects in coupled nanowire dimer

  T. V. Teperik, P. Nordlander, J. Aizpurua, A. G. Borisov
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  ABSTRACT: The optical response of a coupled nanowire dimer is studied using a fully quantum mechanical approach. The translational invariance of the system allows to apply the time--dependent density functional theory for the plasmonic dimer with the largest size considered so far in quantum calculations. Detailed comparisons with results from classical electromagnetic calculations based on local and non local hydrodynamic response, as well as with results of the recently developed quantum corrected model is performed. We show that electron tunneling and dynamical screening are the major nonlocal quantum effects determining the plasmonic modes and field enhancement in the system. Account for the electron tunneling at small junction sizes allows semi-quantitative description of quantum results within classical framework. We also discuss the shortcomings of classical treatments using non-local dielectric permittivities based on hydrodynamic models. Finally, the implications of the actual position of the screening charge density for the plasmon ruler applications are demonstrated.
  02/2013;
• Article: Quantum-well states with image state character for Pb overlayers on Cu(111)

  A. Zugarramurdi, N. Zabala, V. M. Silkin, E. V. Chulkov, A. G. Borisov
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  ABSTRACT: We study theoretically the quantum well states (QWSs) localized in Pb overlayers on Cu(111) surface. Particular emphasis is given to the states with energies close to the vacuum level. Inclusion of the long-range image potential tail into the model potential description of the system allows us to show the effect of hybridization between QWSs and image potential states (ISs). The particle-in-a-box energy sequence characteristic for QWSs evolves into the Rydberg series converging towards the vacuum level. The electron density of the corresponding states is partially moved from inside the metal overlayer into the vacuum. The decay rates due to the inelastic electron-electron scattering decrease with increasing energy, opposite to “conventional” QWSs and similar to the ISs. Many-body and wave packet propagation calculations of the inelastic decay rates are supplemented by simple analysis based on the phase accumulation model and wave-function penetration approximation. This allows an analytical description of the dependence of the QWS/ISs hybridization on different parameters and, in particular, on the overlayer thickness.
  Phys. Rev. B. 08/2012; 86(7).
• Article: Momentum-resolved electron dynamics of image-potential states on Cu and Ag surfaces

  K Schubert, A Damm, S V Eremeev, M Marks, M Shibuta, W Berthold, J Güdde, A G Borisov, S S Tsirkin, E V Chulkov, U Höfer
  Phys. Rev. B. 05/2012; 85(20):205431.
• Article: Attostreaking with metallic nano-objects

  A G Borisov, P M Echenique, A K Kazansky
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  ABSTRACT: The application of atto-second streaking spectroscopy (ASS) to direct time-domain studies of the plasmonic excitations in metallic nano-objects is addressed theoretically. The streaking spectrograms for a rectangular gold nano-antenna and spherical gold clusters are obtained within strong field approximation using classical electron trajectory calculations. The results reported here for spherical clusters are also representative of spherical nano-shells. This study demonstrates that ASS allows for detailed characterization of plasmonic modes, including near-field enhancement, frequency and decay rate. The role of the inhomogeneity of the induced electric fields is also demonstrated.
  New Journal of Physics 02/2012; 14(2):023036. · 4.18 Impact Factor
• Article: Quantum plasmonics: nonlinear effects in the field enhancement of a plasmonic nanoparticle dimer.

  D C Marinica, A K Kazansky, P Nordlander, J Aizpurua, A G Borisov
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  ABSTRACT: A fully quantum mechanical investigation using time-dependent density functional theory reveals that the field enhancement in a coupled nanoparticle dimer can be strongly affected by nonlinear effects. We show that both classical as well as linear quantum mechanical descriptions of the system fail even for moderate incident light intensities. An interparticle current resulting from the strong field photoemission tends to neutralize the plasmon-induced surface charge densities on the opposite sides of the nanoparticle junction. Thus, the coupling between the two nanoparticles and the field enhancement is reduced as compared to linear theory. A substantial nonlinear effect is revealed already at incident powers of 10(9) W/cm(2) for interparticle separation distances as large as 1 nm and down to the touching limit.
  Nano Letters 02/2012; 12(3):1333-9. · 13.20 Impact Factor
• Article: Theoretical study of constant current scanning tunneling spectroscopy in Pb overlayers

  A. Zugarramurdi, N. Zabala, A. G. Borisov, E. V. Chulkov
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  ABSTRACT: We present a theoretical study of the constant current scanning tunneling spectroscopy of quantum well states localized in Pb(111) overlayers on Cu(111) surfaces. The distance-voltage characteristic of the tunneling junction is obtained with a mixed approach. The wave packet propagation technique is applied to describe electron tunneling from the tip into the sample, and the density functional calculations provide the necessary inputs for the one-dimensional model potential representation of the system. The excited-state population decay mechanisms via inelastic electron-electron and electron-phonon interactions are taken into account with a bias-dependent absorbing potential introduced in the metal. Our results are in good agreement with recent experimental studies [ Phys. Rev. Lett. 102 196102 (2009), Phys. Rev. B 81 205438 (2010)] over the energy range where the free-electron description of the Pb overlayer used here applies. We find that at high bias the quantum well states experience a Stark energy shift and partially acquire a character of field emission resonances. The present model study also sheds light at the experimentally observed departure of the energies of the quantum well states from the particle-in-a-box prediction for the bias above 4 eV. The measured trend can be consistently explained as due to the departure of the realistic Pb band structure in the Γ-L direction from free-electron parabola when the electron momentum approaches the Γ point.
  Phys. Rev. B. 09/2011; 84(11).
• Article: Comment on "Phase contribution of image potential on empty quantum well states in Pb islands on the Cu(111) surface".

  A Zugarramurdi, N Zabala, A G Borisov, E V Chulkov
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  ABSTRACT: A Comment on the Letter by M. C. Yang et al., Phys. Rev. Lett. 102, 196102 (2009). The authors of the Letter offer a Reply.
  Physical Review Letters 06/2011; 106(24):249601; author reply 249602. · 7.37 Impact Factor
• Source

  Available from: Naomi J Halas

  Article: Optical spectroscopy of conductive junctions in plasmonic cavities.

  O Pérez-González, N Zabala, A G Borisov, N J Halas, P Nordlander, J Aizpurua
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  ABSTRACT: The optical properties of a nanoparticle dimer bridged by a conductive junction depend strongly on the junction conductivity. As the conductivity increases, the bonding dimer plasmon blueshifts and broadens. For large conductance, a low energy charge transfer plasmon also appears in the spectra with a line width that decreases with increasing conductance. A simple physical model for the understanding of the spectral feature is presented. Our finding of a strong influence of junction conductivity on the optical spectrum suggests that plasmonic cavities might serve as probes of molecular conductance at elevated frequencies not accessible through electrical measurements.
  Nano Letters 08/2010; 10(8):3090-5. · 13.20 Impact Factor
• Source

  Available from: Ricardo Diez Muino

  Article: Lifetime of electronic excitations in metal nanoparticles

  M Quijada, R D Muino, A G Borisov, J A Alonso, P M Echenique
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  ABSTRACT: Electronic excitations in metal particles with sizes up to a few nanometers are shown to have a one-electron character when a laser pulse is applied off the plasmon resonance. The calculated lifetimes of these excitations are in the femtosecond timescale but their values are substantially different from those in bulk. This deviation can be explained from the large weight of the excitation wave function in the nanoparticle surface region, where dynamic screening is significantly reduced. The well-known quadratic dependence of the lifetime with the excitation energy in bulk breaks down in these finite-size systems.
  New Journal of Physics. 01/2010; 12.
• Article: Linewidth of a cesium adatom resonance on Ag(111)

  M. Ziegler, J. Kröger, R. Berndt, A. G. Borisov, J. P. Gauyacq
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  ABSTRACT: Single Cs atoms adsorbed on Ag(111) induce a resonance appearing just below the threshold of the quasi-two-dimensional Shockley-type surface-state continuum. Spectroscopic analysis using a cryogenic scanning tunneling microscope and theoretical modeling are used to identify the importance of the various contributions to the linewidth and to the decay of the resonance: resonant charge transfer, inelastic transitions, and adsorbate vibrations perpendicular to the surface.
  Physical review. B, Condensed matter 01/2009; 79(7):75401.
• Source

  Available from: ehu.es

  Article: Pi resonance of chemisorbed alkali atoms on noble metals.

  A G Borisov, V Sametoglu, A Winkelmann, A Kubo, N Pontius, J Zhao, V M Silkin, J P Gauyacq, E V Chulkov, P M Echenique, H Petek
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  ABSTRACT: We have performed a joint experimental and theoretical study of the unoccupied electronic structure of alkali adsorbates on the (111) surfaces of Cu and Ag. Combining angle- and time-resolved two-photon photoemission spectroscopy with wave packet propagation calculations we show that, along with the well known sigma resonance oriented along the surface normal, there exist long-lived alkali-localized resonances oriented parallel to the surface (pi symmetry). These new resonances are stabilized by the projected band gap of the substrate and emerge primarily from the mixing of the p and d Rydberg orbitals of the free alkali atom modified by the interaction with the surface.
  Physical Review Letters 01/2009; 101(26):266801. · 7.37 Impact Factor
• Article: Theoretical study of excited electronic states at surfaces, link with photo-emission and photo-desorption experiments

  J-P Gauyacq, A G Borisov, A K Kazansky
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  ABSTRACT: Excited electronic states at surfaces play a very important role in a variety of surface processes. These excited states have a finite lifetime due to electron-transfer processes and their efficiency as reaction intermediates depends crucially on their lifetime. A review of several physical situations, where an excited electronic state localized on an atom interacting with a metal surface intervenes in a surface process, is presented with an emphasis on the way the metal electronic structure influences the excited state dynamics. Examples are chosen among the alkali/metal systems, stressing how the same transient electronic state can influence different dynamical processes.
  Journal of Physics Conference Series 11/2008; 133(1):012009.
• Article: Time‐dependent density functional calculation of the energy loss of antiprotons colliding with metallic nanoshells

  M. Quijada, A. G. Borisov, R. Díez Muiño
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  ABSTRACT: Time-dependent density functional theory is used to study the interaction between antiprotons and metallic nanoshells. The ground state electronic properties of the nanoshell are obtained in the jellium approximation. The energy lost by the antiproton during the collision is calculated and compared to that suffered by antiprotons traveling in metal clusters. The resulting energy loss per unit path length of material in thin nanoshells is larger than the corresponding quantity for clusters. It is shown that the collision process can be interpreted as the antiproton crossing of two nearly bi-dimensional independent metallic systems. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
  Physica Status Solidi (A) Applications and Materials 05/2008; 205(6):1312 - 1316. · 1.46 Impact Factor
• Article: Bound States in the continuum in photonics.

  D C Marinica, A G Borisov, S V Shabanov
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  ABSTRACT: With examples of two parallel dielectric gratings and two arrays of thin parallel dielectric cylinders, it is shown that the interaction between trapped electromagnetic modes can lead to scattering resonances with practically zero width. Such resonances are the bound states in the radiation continuum first discovered in quantum systems by von Neumann and Wigner. Potential applications of such photonic systems include: large amplification of electromagnetic fields within photonic structures and, hence, enhancement of nonlinear phenomena, biosensing, as well as perfect filters and waveguides for a particular frequency, and impurity detection.
  Physical Review Letters 05/2008; 100(18):183902. · 7.37 Impact Factor
• Source

  Available from: ehu.es

  Article: Lifetime of an adsorbate excitation modified by a tunable two-dimensional substrate

  M Wiesenmayer, M Bauer, S Mathias, M Wessendorf, E V Chulkov, V M Silkin, A G Borisov, J.-P Gauyacq, P M Echenique, M Aeschlimann
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  ABSTRACT: The coupling efficiency between an adsorbate and a two-dimensional substrate is probed by real-time monitoring of the ultrafast charge transfer between a Cs atom and an ultrathin silver film of varying thickness adsorbed on a Cu111 surface. For the first two monolayers of the silver film, a reduction in the resonance lifetime of the cesium 6s-6p hybrid state of approximately 35% is observed. When the silver coverage further increases, the resonance lifetime stays constant at a value close to the value for Cs adsorption on a bulk Ag111 surface. Both the one-electron resonant and the multielectron inelastic contributions to the adsorbate-substrate charge transfer are theoretically evaluated based on wave-packet propagation and GW approximation. The results support the experimental findings and allow us to assign the observed dependence of the lifetime change in the multielectron inelastic contribution to the electron transfer rate between the Cs resonance and the very top atomic layers of the substrate.
  Physical Review B 01/2008; 78:245410. · 3.69 Impact Factor
• Article: Interaction Between Overlapping Quasi-Stationary States: He (2 1S and 2 1P) Levels in Front of an Aluminium Surface

  G. E. Makhmetov, A. G. Borisov, D. Teillet-Billy, J. P. Gauyacq
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  ABSTRACT: The interaction of He (2 1S) and He (2 1P) atoms with an aluminium surface is studied using the coupled-angular-mode method. The energy positions and widths of the perturbed atomic levels are determined as functions of the atom-surface distance Z. They display a very unusual behaviour: when Z decreases the two states "attract" each other when they start to overlap, they almost coalesce and then split with very different widths. This is quite different from the usual picture where interacting states repel each other. This behaviour is attributed to the existence of an imaginary coupling term between the two quasi-stationary states, which corresponds to indirect transitions via the metal surface continuum.
  EPL (Europhysics Letters) 07/2007; 27(3):247. · 2.17 Impact Factor
• Article: Excited states of Na nanoislands on the Cu(111) surface

  T. Hakala, M. J. Puska, A. G. Borisov, V. M. Silkin, N. Zabala, E. V. Chulkov
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  ABSTRACT: Electronic states of one monolayer high Na nanoislands on the Cu(111) surface are studied as a function of the nanoisland size. Properties of nanoislands such as one-electron states, the electron density, and the associated potential are obtained self-consistently within the density-functional formalism using a one-dimensional pseudopotential for the Cu(111) substrate and the jellium model for Na. A wave packet propagation method is used to study the energies and lifetimes of quasistationary states localized at Na islands. For very large islands, island-localized states merge into the two-dimensional continuum of the Na quantum well state. Thus, we assign the quasistationary states studied as arising from the quantization of the two-dimensional quantum well continuum due to the finite island size. The scattering at the island boundaries results in the energy-conserving resonant electron transfer into the continuum of the substrate states broadening the island-localized states into resonances.
  Phys. Rev. B. 04/2007; 75(16).
• Article: Quantum scattering of fast atoms and molecules on surfaces.

  P Rousseau, H Khemliche, A G Borisov, P Roncin
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  ABSTRACT: We present evidence for the diffraction of light keV atoms and molecules grazingly scattered on LiF(001) and NaCl(001) surfaces. At such energies, the de Broglie wavelength is 2 orders of magnitude smaller that the mean thermal atomic displacement in the crystal. Thus, no coherent scattering was expected and interaction of keV atoms with surfaces is routinely treated with classical mechanics. We show here that well-defined diffraction patterns can be observed indicating that, for grazing scattering, the pertinent wavelength is that associated with the slow motion perpendicular to the surface. The experimental data are well reproduced by an ab initio calculation.
  Physical Review Letters 02/2007; 98(1):016104. · 7.37 Impact Factor
• Source

  Available from: physik.uni-kl.de

  Article: Excited states in the alkali/noble metal surface systems: A model system for the study of charge transfer dynamics at surfaces

  J.P. Gauyacq, A.G. Borisov, M. Bauer
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  ABSTRACT: The low coverage adsorption of alkalis on metal surfaces induces excited states localised on the adsorbate. In the case of noble metal substrates, these excited states can exhibit a very long lifetime, up to tens of fs in the Cs/Cu(1 1 1) system. We review recent experimental and theoretical investigations of alkalis adsorbed on noble metal surfaces, with emphasis on the characteristics of the alkali-induced excited states, the origin of their long lifetimes, and the consequences for the adsorbate dynamics. The possibility of long-lived resonances in other adsorbate/substrate systems is also discussed.
  Progress in Surface Science 01/2007; 82:244-292. · 8.64 Impact Factor
• Chapter: Dynamics of Resonant Electron Transfer in the Interaction Between an Atom and a Metallic Surface

  J. P. Gauyacq, A. G. Borisov
  12/2006: pages 87-109;