J. P. Toennies

Publications (55)73.81 Total impact

• Article: Giorgio Benedek: an extraordinary universal scientist.

  M Bernasconi, S Miret-Artés, J P Toennies
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  ABSTRACT: Please see PDF for the full text of the article.
  Journal of Physics Condensed Matter 02/2012; 24(10):100401. · 2.55 Impact Factor
• Article: Dynamics of low-dimensional systems.

  M Bernasconi, S Miret-Artés, J P Toennies
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  ABSTRACT: With the development of techniques for high-resolution inelastic helium atom scattering (HAS), electron scattering (EELS) and neutron spin echo spectroscopy, it has become possible, within approximately the last thirty years, to measure the dispersion curves of surface phonons in insulators, semiconductors and metals. In recent years, the advent of new experimental techniques such as (3)He spin-echo spectroscopy, scanning inelastic electron tunnel spectroscopy, inelastic x-ray scattering spectroscopy and inelastic photoemission have extended surface phonon spectroscopy to a variety of systems. These include ultra-thin metal films, adsorbates at surface and elementary processes where surface phonons play an important role. Other important directions have been actively pursued in the past decade: the dynamics of stepped surfaces and clusters grown on metal surfaces, due to their relevance in many dynamical and chemical processes at surfaces, including heterogeneous catalysis; clusters; diffusion etc. The role of surface effects in these processes has been conjectured since the early days of surface dynamics, although only now is the availability of ab initio approaches providing those conjectures with a microscopic basis. Last but not least, the investigation of non-adiabatic effects, originating for instance from the hybridization (avoided crossing) of the surface phonons branches with the quasi 1D electron-hole excitation branch, is also a challenging new direction. Furthermore, other elementary oscillations such as surface plasmons are being actively investigated. The aforementioned experimental breakthroughs have been accompanied by advances in the theoretical study of atom-surface interaction. In particular, in the past decade first principles calculations based on density functional perturbation theory have boosted the theoretical study of the dynamics of low-dimensional systems. Phonon dispersion relations of clean surfaces, the dynamics of adsorbates, and the vibrational spectra of clusters and carbon-based nanostructures, just to name a few of the low-dimensional systems addressed in this special issue, can be both accurately computed from first principles and measured experimentally. Even less computationally demanding semi-empirical simulations based on tight-binding or continuum models play a crucial role in assessing, for instance, the interplay between morphology, defects and the elastic properties of low-dimensional systems. The impressive amount of work and progress achieved in the past decade within the general theory and spectroscopy of the dynamics of low-dimensional systems is marked by several relevant trends that are exemplified by the contributions gathered together in this special issue. They span a wide spectrum of experimental and theoretical methods applied to the study of the dynamical properties of low-dimensional systems and new emerging phenomena at the nanoscale, such as the peculiar optical properties of ring shaped quantum dots, plasmon dynamics in metallic nanoclusters and the relaxation dynamics of nanomagnets. This issue is dedicated to our esteemed colleague Giorgio Benedek on the occasion of his 70th birthday. It collects together a number of papers written by authors from all over the world with a recognized reputation in the above mentioned fields where Giorgio Benedek has made important and fundamental contributions. Dynamics of low-dimensional systems contents Narratives Giorgio Benedek: an extraordinary universal scientist M Bernasconi, S Miret-Artés and J P Toennies Helium and carbon: two friends for life Giorgio Benedek Special Issue Papers Temperature dependence in atom-surface scattering Eli Pollak and J R Manson Density functional study of the decomposition pathways of SiH(3) and GeH(3) at the Si(100) and Ge(100) surfaces M Ceriotti, F Montalenti and M Bernasconi Comparative study of vibrations in submonolayer structures of potassium on Pt(111) G G Rusina, S V Eremeev, S D Borisova and E V Chulkov Surface phonons on Pb(111) I Yu Sklyadneva, R Heid, K-P Bohnen, P M Echenique and E V Chulkov Using evidence from nanocavities to assess the vibrational properties of external surfaces G F Cerofolini, F Corni, S Frabboni, G Ottaviani, E Romano, R Tonini and D Narducci Magnetic properties and relaxation dynamics of a frustrated Ni(7) molecular nanomagnet E Garlatti, S Carretta, M Affronte, E C Sañudo, G Amoretti and P Santini A theoretical study of rotational and translational diffusion dynamics of molecules with a six-fold point symmetry adsorbed on a hexagonal lattice by neutron scattering I Calvo-Almazán, S Miret-Artés and P Fouquet Vibrational dynamics and surface structure of Bi(111) from helium atom scattering measurements M Mayrhofer-Reinhartshuber, A Tamtögl, P Kraus, K H Rieder and W E Ernst Double and triple ionization of silver clusters by electron impactAvik Halder, Anthony Liang, Chunrong Yin and Vitaly V Kresin Scattering of O(2) from a graphite surface W W Hayes, Junepyo Oh, Takahiro Kondo, Keitaro Arakawa, Yoshihiko Saito, Junji Nakamura and J R Manson Zero-phonon lines of systems with different dimensions and unconventional vibronic interactions V Hizhnyakov A kinetic Monte Carlo approach to investigate antibiotic translocation through bacterial porins Matteo Ceccarelli, Attilio V Vargiu and Paolo Ruggerone Quantum Zeno and anti-Zeno effects in surface diffusion of interacting adsorbates H C Peñate-Rodrìguez, R Martìnez-Casado, G Rojas-Lorenzo, A S Sanz and S Miret-Artés Weakly bound finite systems: ((4)He)(N)-Rb(2)((3)Σ(u)), clustering structures from a quantum Monte Carlo approach D López-Durán, R Rodrìguez-Cantano, T González-Lezana, G Delgado-Barrio, P Villarreal, E Yurtsever and F A Gianturco Multiphonon atom-surface scattering from corrugated surfaces: derivation of the inelastic scattering spectrum for diffraction statesBranko Gumhalter Probing the non-pairwise interactions between CO molecules moving on a Cu(111) surfacePepijn R Kole, Holly Hedgeland, Andrew P Jardine, William Allison, John Ellis and Gil Alexandrowicz Fast emission dynamics in droplet epitaxy GaAs ring-disk nanostructures integrated on SiL Cavigli, S Bietti, M Abbarchi, C Somaschini, A Vinattieri, M Gurioli, A Fedorov, G Isella, E Grilli and S Sanguinetti Assessing the composition of hetero-epitaxial islands via morphological analysis: an analytical model matching GeSi/Si(001) dataR Gatti, F Pezzoli, F Boioli, F Montalenti and Leo Miglio Carbon sp chains in graphene nanoholesIvano E Castelli, Nicola Ferri, Giovanni Onida and Nicola Manini Elastic fields and moduli in defected grapheneRiccardo Dettori, Emiliano Cadelano and Luciano Colombo Tuning the plasmon energy of palladium-hydrogen systems by varying the hydrogen concentrationV M Silkin, R Dìez Muiño, I P Chernov, E V Chulkov and P M Echenique Plasmon tsunamis on metallic nanoclustersA A Lucas and M Sunjic Ab initio characterization of graphene nanoribbons and their polymer precursorsRengin Peköz, Xinliang Feng and Davide Donadio First-principles phonon calculations of Fe(4+) impurity in SrTiO(3)E Blokhin, E A Kotomin and J Maier Phonon dispersion of quasi-freestanding graphene on Pt(111)Antonio Politano, Antonio Raimondo Marino and Gennaro Chiarello Vibrations of Au(13) and FeAu(12) nanoparticles and the limits of the Debye temperature conceptGhazal Shafai, Marisol Alcántara Ortigoza and Talat S Rahman.
  Journal of Physics Condensed Matter 02/2012; 24(10):100301. · 2.55 Impact Factor
• Chapter: Quasielastic Helium Scattering Studies of Surface Diffusion: The Diffusion Barrier

  A. P. Graham, J. P. Toennies
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  ABSTRACT: Some results of recent quasielastic helium scattering (QHAS) on the surface diffusion of adatoms and adsorbates are reviewed. Particular emphasis is placed on the evaluation of the effective diffusion barrier energies measured and their dependence on the system and temperature range.
  06/2011: pages 1-10;
• Article: Comparison of Helium Atom Scattering Surface Phonon Dispersion Curves of the (1 × 2) Reconstructed Au(110) Surface with First-Principle Calculations

  A. M. Lahee, J. P. Toennies, Ch. Wöll, K. P. Bohnen, K. M. Ho
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  ABSTRACT: For the Au(110)-reconstructed surface we present a comparison of surface phonon modes measured with inelastic He-scattering and calculated from first principles. For the point use of bulk force constants does not explain the observed vibrational modes, while the microscopic first principles results give good agreement with the experiment. In contrast to recent results obtained with the semiempirical "glue"-model our microscopic calculations do not support the claim of anomalous high-frequency modes at this surface.
  EPL (Europhysics Letters) 07/2007; 10(3):261. · 2.17 Impact Factor
• Article: Evidence for a Charge Density Wave Driven Reconstruction in W(001)

  H.-J. Ernst, E. Hulpke, J. P. Toennies
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  ABSTRACT: A charge density wave (CDW) mechanism is shown to explain the anomalous temperature-dependent diffraction peaks observed by high-resolution He scattering experiments accompanying the reconstruction of the clean W(001) surface. This model also accounts for the differences found in the electron and the He atom diffraction patterns.
  EPL (Europhysics Letters) 07/2007; 10(8):747. · 2.17 Impact Factor
• Article: Experimental determination of the vibrations and diffusion of isolated CO molecules moving parallel to a Pt(111) surface

  A. P. Graham, J. P. Toennies
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  ABSTRACT: The full-width half-maxima (FWHM) of the 6 meV parallel frustrated translation mode of CO chemisorbed on Pt(111) (Eads =1.5 eV) have been measured using high-resolution helium atom scattering over the temperature range 50–200 K for four different isotopomers and the results are compared with earlier measurements on CO/Cu(001), which has a much lower adsorption energy of 0.7 eV. The FWHM is independent of the temperature and isotopomer and corresponds to a vibrational lifetime of 1.37±0.22 ps. The observed lifetime is attributed to both phononic and electronic frictional damping and is used, in conjunction with quasi-elastic helium scattering measurements, to estimate the diffusion barrier to be Ebarr ~ 130 meV.
  EPL (Europhysics Letters) 01/2007; 42(4):449. · 2.17 Impact Factor
• Article: He atom scattering and theoretical study of the surface phonons of a simple benchmark system: Xe(111)

  Antonio Šiber, B. Gumhalter, A.P. Graham, J.P. Toennies
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  ABSTRACT: Low-energy inelastic helium atom scattering measurements of the Xe(111) surface phonon dispersion curves are presented and compared with the results of extensive lattice dynamics analysis and complete one-phonon and multiphonon scattering calculations in the exponentiated distorted-wave Born approximation. The comparisons show that the Xe(111) surface phonon dispersion curves and the individual excitation time-of-flight peak; intensities are well described using the gas-phase He-Xe and Xe-Xe pair potentials.
  Physical Review B 03/2001; 63(11):115411. · 3.69 Impact Factor
• Article: Correlation between elastic and inelastic atom scattering from single adsorbed molecules

  B. H. Choi, A. P. Graham, K. T. Tang, J. P. Toennies
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  ABSTRACT: High resolution measurements of the angular distributions for the elastic and inelastic scattering of helium atoms from the translational vibrations (T modes) of single CO molecules on Pt(111) agree quantitatively with a simple transformation which predicts the inelastic cross section from the measured elastic cross section. The new theory predicts not only the inelastic interference structures and their correlations with the elastic channel, but also the individual state-to-state transitions. © 2001 American Institute of Physics.
  The Journal of Chemical Physics. 02/2001; 114(7):2883-2886.
• Article: Comment on “Surface diffusion potential energy surfaces from first principles: CO chemisorbed on Pt{110}” [J. Chem. Phys. 111, 9461 (1999)]

  A. P. Graham, J. P. Toennies
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  ABSTRACT: In a recent article Ge and King [J. Chem. Phys. 111, 9461 (1999)] question, on the basis of their recent density functional calculations, the interpretation of quasielastic helium atom scattering experiments on surface diffusion. In this comment we attempt to clarify a number of misunderstandings and justify the methods used in the data analysis. © 2001 American Institute of Physics.
  The Journal of Chemical Physics 01/2001; 114(2):1051-1052. · 3.33 Impact Factor
• Article: Three-body exchange energies in H3 and He3 calculated by the surface integral method

  U. Kleinekathöfer, T. I. Sachse, K. T. Tang, J. P. Toennies, C. L. Yiu
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  ABSTRACT: Repulsive three-body exchange energies are calculated for H3 and He3 using a new method based on an extension of the surface integral method to three-body interactions. The dependence of the three-body exchange energies on the internuclear distances between 5 and 10 a0 is investigated for equilateral configurations. The angular dependence is also studied for geometries in which two distances are fixed at equal distances. Very good agreement with other calculations at the same level of approximation is obtained for H3 as well as for He3. The relative importance of the different electron permutations in He3 is discussed. © 2000 American Institute of Physics.
  The Journal of Chemical Physics 07/2000; 113(3):948-956. · 3.33 Impact Factor
• Article: Helium atom scattering from isolated CO molecules on a Pt(111) surface: Experiment versus close-coupling calculations for a realistic He–CO potential

  B. H. Choi, A. P. Graham, K. T. Tang, J. P. Toennies
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  ABSTRACT: The angular dependence of the elastic scattering of helium atoms from a low coverage (ΘCO = 0.03) of randomly distributed isolated CO molecules adsorbed on a Pt(111) surface has been measured over a wide range of incident helium atom beam energies between Ei = 5.25 and 62.1 meV. The results are compared with a close-coupling theory for a realistic He–CO potential. From a best fit of the experimental results the distance of the molecule from the surface and a modified gas phase He–CO potential are obtained. © 2000 American Institute of Physics.
  The Journal of Chemical Physics 06/2000; 112(23):10538-10547. · 3.33 Impact Factor
• Source

  Available from: Branko Gumhalter

  Article: Combined He-atom scattering and theoretical study of the low energy vibrations of physisorbed monolayers of Xe on Cu(111) and Cu(001)

  A. Siber, B. Gumhalter, J. Braun, A. P. Graham, M. F. Bertino, J. P. Toennies, D. Fuhrmann, Ch. Wöll
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  ABSTRACT: The surface phonon dispersion curves of commensurate Xe monolayers on Cu(111) and incommensurate Xe monolayers on Cu(001) surfaces have been measured using He atom scattering (HAS) time of flight (TOF) spectroscopy. The TOF spectra are interpreted by combining quantum scattering calculations with the dynamical matrix description of the surface vibrations. Both a vertically polarized Einstein-like mode and another, acoustic-like mode of dominantly longitudinal character, are identified. The latter mode is characterized by the presence and absence of the zone center frequency gap in the commensurate and incommensurate adlayers, respectively. The microscopic description of the TOF spectral intensities is based on the extensive theoretical studies of the interplay of the phonon dynamics, projectile-surface potentials, multi-quantum interference and projectile recoil, and their effect on the HAS spectra. Both single and multi-quantum spectral features observed over a wide range of He atom incident energies and substrate temperatures are successfully explained by the theory.
  02/2000;
• Source

  Available from: Branko Gumhalter

  Article: Study of energy transfer in helium atom scattering from surfaces

  A. Siber, B. Gumhalter, J. P. Toennies
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  ABSTRACT: Recently developed quantum mechanical theory of inelastic He atom scattering (HAS) from solid surfaces is employed to analyze the energy transfer between projectile particles (thermal energy He-atoms) and vibrational degrees of freedom (phonons) characteristic of a variety of experimentally studied surfaces. We have first calculated the angular resolved energy transfer which can be directly compared with the values deducible from the HAS time-of-flight spectra and a good agreement with experimental data has been found. This enabled us to calculate the total or angular integrated energy transfer, which is of paramount importance in the studies of gas-surface scattering, but is neither accessible in HAS (which yields only the angular resolved quantities), nor in the wind tunnel measurements for surfaces whose atomic composition and cleanliness must be maintained during the experiment. Here we present the results for prototype collision systems of this kind, viz. He => Cu(001), He => Xe/Cu(111) and He => Xe(111) which are representative of the very different types of surface vibrational dynamics and thereby provide an insight into some common properties of energy transfer in gas-surface scattering.
  10/1999;
• Article: Boundary condition determined wave functions for the ground states of one- and two-electron homonuclear molecules

  S. H. Patil, K. T. Tang, J. P. Toennies
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  ABSTRACT: Simple analytical wave functions satisfying appropriate boundary conditions are constructed for the ground states of one-and two-electron homonuclear molecules. Both the asymptotic condition when one electron is far away and the cusp condition when the electron coalesces with a nucleus are satisfied by the proposed wave function. For H2+, the resulting wave function is almost identical to the Guillemin–Zener wave function which is known to give very good energies. For the two electron systems H2 and He2++, the additional electron–electron cusp condition is rigorously accounted for by a simple analytic correlation function which has the correct behavior not only for r12→0 and r12→∞ but also for R→0 and R→∞, where r12 is the interelectronic distance and R, the internuclear distance. Energies obtained from these simple wave functions agree within 2×10−3 a.u. with the results of the most sophisticated variational calculations for all R and for all systems studied. This demonstrates that rather simple physical considerations can be used to derive very accurate wave functions for simple molecules thereby avoiding laborious numerical variational calculations. © 1999 American Institute of Physics.
  The Journal of Chemical Physics 10/1999; 111(16):7278-7289. · 3.33 Impact Factor
• Source

  Available from: Branko Gumhalter

  Article: Recovery temperature for nonclassical energy transfer in atom-surface scattering

  B. Gumhalter, A. Siber, J. P. Toennies
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  ABSTRACT: Nonperturbative expressions are derived for the angular resolved energy transfer spectra in the quantum regime of multiphonon scattering of inert gas atoms from surfaces. Application to He atom scattering from a prototype heatbath Xe/Cu(111) shows good agreement with experiments. This enables a full quantum calculation of the total energy transfer $\mu$ and therefrom the much debated recovery or equilibrium temperature $T_{r}$ characteristic of zero energy transfer in gas-surface collisions in the free molecular flow regime. Classical universal character of $\mu$ and $T_{r}$ is refuted. Comment: 3 figures
  09/1999;
• Article: The generalized Heitler–London theory for the H3 potential energy surface

  U. Kleinekathöfer, K. T. Tang, J. P. Toennies, C. L. Yiu
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  ABSTRACT: A systematic perturbation theory has been developed to analyze the terms contributing to the H3 potential energy surface. Group theory is used to find the irreducible representations of the Hamiltonian matrix elements which then are decoupled to their simplest level. In the case of diatomic molecules, this approach leads naturally to the Generalized Heitler–London (GHL) theory derived previously [K. T. Tang and J. P. Toennies, J. Chem. Phys. 95, 5918 (1991)]. Many previous semi-empirical potential surfaces for the H3 triatomic system including the well known LEPS surface are examined in the light of the present results. In particular, the Cashion–Herschbach (or diatomics-in-molecules without overlap) surface is shown to encompass far more information than previously recognized. The new theory now contains all the terms needed for an exact perturbation calculation of the potential energy surface. © 1999 American Institute of Physics.
  The Journal of Chemical Physics 08/1999; 111(8):3377-3386. · 3.33 Impact Factor
• Article: Recovery temperature for nonclassical energy transfer in atom-surface scattering

  B. Gumhalter, A. Šiber, J.P. Toennies
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  ABSTRACT: Nonperturbative expressions are derived for the angular resolved energy transfer spectra in the quantum regime of multiphonon scattering of inert gas atoms from surfaces. Application to He atom scattering from a prototype heat bath Xe/Cu(111) shows good agreement with experiments. This enables a full quantum calculation of the total energy transfer mu and from this the much debated recovery or equilibrium temperature T-r characteristic of zero energy transfer in gas-surface collisions in the free molecular flow regime. The classical universal character of mu, and T-r is refuted.
  Physical Review Letters 08/1999; 83(7-83):1375. · 7.37 Impact Factor
• Article: Study of energy transfer in helium atom scattering from surfaces

  A. Šiber, B. Gumhalter, J.P. Toennies
  [show abstract] [hide abstract]
  ABSTRACT: Recently developed quantum mechanical theory of inelastic He atom scattering (HAS) from solid surfaces is employed to analyze the energy transfer between projectile particles (thermal energy He-atoms) and vibrational degrees of freedom (phonons) characteristic of a variety of experimentally studied surfaces. We have first calculated the angular resolved energy transfer which can be directly compared with the values deducible from the HAS time-of-flight spectra and a good agreement with experimental data has been found. This enabled us to calculate the total or angular integrated energy transfer, which is of paramount importance in the studies of gas-surface scattering, but is neither accessible in HAS (which yields only the angular resolved quantities), nor in the wind tunnel measurements for surfaces whose atomic composition and cleanliness must be maintained during the experiment. Here we present the results for prototype collision systems of this kind, viz. He --> Cu(0 0 1), He --> Xe/Cu(1 1 1) and He --> Xe(1 1 1) which are representative of the very different types of surface vibrational dynamics and thereby provide an insight into some common properties of energy transfer in gas-surface scattering.
  Vacuum 07/1999; 54(1-4-54):315. · 1.32 Impact Factor
• Article: Erratum: Inelastic focusing effects in atom-surface scattering [Phys. Rev. B 57, R9455 (1998)]

  A. Glebov, J. R. Manson, S. Miret-Artés, J. G. Skofronick, J. P. Toennies
  Phys. Rev. B. 03/1999; 59(11).
• Article: Combined He-atom scattering and theoretical study of the low-energy vibrations of physisorbed monolayers of Xe on Cu(111) and Cu(001)

  A. Šiber, B. Gumhalter, J. Braun, A.P. Graham, M.F. Bertino, J.P. Toennies, D. Fuhrmann, C. Woll
  [show abstract] [hide abstract]
  ABSTRACT: The surface-phonon-dispersion curves of commensurate Xe monolayers on Cu(111) and incommensurate monolayers on Cu(001) surfaces have been measured using He-atom scattering (HAS) time-of-flight (TOF) spectroscopy. The TOP spectra are interpreted by combining quantum scattering calculations with the dynamical matrix description of the surface vibrations. Both a vertically polarized Einstein-like mode and another, acousticlike mode of dominantly longitudinal character are identified, The latter mode is characterized by the presence and absence of the zone-center frequency gap in the commensurate and incommensurate adlayers, respectively, The microscopic description of the,TOF spectral intensities is based on the extensive theoretical studies of,the interplay of the phonon dynamics, projectile-surface potentials, multiple quantum interference, and projectile recoil, and. their effect on the HAS spectra. Both single and multiple quantum spectral features observed over a wide range of He-atom incident energies and substrate temperatures are successfully explained by the theory. [S0163-1829(99)10507-1].
  Physical Review B 02/1999; 59(8-59):5898. · 3.69 Impact Factor