Peer-reviewed Publications |
Canneson, D., Le Moal, E., Cao, S., Quélin, X., Dallaporta, D., Dujardin, G., & Boer-Duchemin, E. (2016). Surface plasmon polariton beams from an electrically excited plasmonic crystal. Opt. Express, 24(23), 26186–26200.
Résumé: Surface plasmon polariton (SPP) beams with an in-plane angular spread of 8° are
produced by electrically exciting a 2D plasmonic crystal using a scanning tunneling microscope (STM). The plasmonic crystal consists of a gold nanoparticle (NP) array on a thin gold film on a glass substrate and it is the inelastic tunnel electrons (IET) from the STM that provide a localized and spectrally broadband SPP source. Surface waves on the gold film are shown to be essential for the coupling of the local, electrical excitation to the extended NP array, thus leading to the creation of SPP beams. A simple model of the scattering of SPPs by the array is used to explain the origin and direction of the generated SPP beams under certain conditions. In order to take into account the broadband spectrum of the source, calculations realized using finite-difference time-domain (FDTD) methods are obtained, showing that bandgaps for SPP propagation exist for certain wavelengths and indicating how changing the pitch of the NP array may enhance the SPP beaming effect.
|
|
Choi, D. - J., Robles, R., Gauyacq, J. - P., Rubio-Verdu, C., Lorente, N., & Ignacio Pascual, J. (2016). Spin-polarised edge states in atomic Mn chains supported on Cu2N/Cu (100). J. Phys. Condens. Matter., 28(23), 23lt01.
Résumé: Scanning tunnelling microscopy and density functional theory studies of manganese chains adsorbed on Cu2N/Cu (100) reveal an unsuspected electronic edge state at [Formula: see text] eV above the Fermi energy. This Tamm-like state is strongly localised to the terminal Mn atoms of the chain and fully spin polarised. However, no equivalence is found for occupied states, and the electronic structure at [Formula: see text] -1 eV is mainly spin unpolarised due to the extended p-states of the N atoms that mediate the coupling between the Mn atoms in the chain. The spin polarisation of the edge state is affected by the antiferromagnetic ordering of the chains leading to non-trivial consequences.
|
|
|
Choi, D. - J., Robles, R., Gauyacq, J. - P., Ternes, M., Loth, S., & Lorente, N. (2016). Structural and magnetic properties of FeMnx chains (x=1–6) supported on Cu2N/Cu (100). Phys. Rev. B, 94(8), 085406.
|
|
Dujardin, G., Boer-Duchemin, E., Le Moal, E., Mayne, A. J., & Riedel, D. (2016). DIET (Dynamics at surfaces Induced by Electronic Transitions) at the nanoscale. Surf. Sci., 643, 13–17.
Résumé: We review the long maturing evolution of DIET (Dynamics at surfaces Induced by Electronic Transitions) that began in the 1960s when Menzel, Gomer and Redhead proposed their famous stimulated desorption model. DIET entered the « nanoscale » in the 1990s when researchers at Bell Labs and IBM realized that the Scanning Tunneling Microscope (STM) could be used as an atomic size source of electrons to electronically excite individual atoms and molecules at surfaces. Resonant and radiant Inelastic Electron Tunneling (IET) using the STM have considerably enlarged the range of applications of DIET. Nowadays, « DIET at the nanoscale » covers a broad range of phenomena at the atomic-scale. This includes molecular dynamics (dissociation, desorption, isomerization, displacement, chemical reaction), vibrational spectroscopy and dynamics, spin spectroscopy and manipulation, luminescence spectroscopy, Raman spectroscopy and plasmonics. Future trends of DIET at the nanoscale offer exciting prospects for new methods to control light and matter at the nanoscale.
|
|
Gruber, E., Wilhelm, R. A., Petuya, R., Smejkal, V., Kozubek, R., Hierzenberger, A., Bayer, B. C., Aldazabal, I., Kazansky, A. K., Libisch, F., Krasheninnikov, A. V., Schleberger, M., Facsko, S., Borisov, A. G., Arnau, A., & Aumayr, F. (2016). Ultrafast electronic response of graphene to a strong and localized electric field. Nat. Commun., 7, 13948.
Résumé: The way conduction electrons respond to ultrafast external perturbations in low dimensional materials is at the core of the design of future devices for (opto)electronics, photodetection and spintronics. Highly charged ions provide a tool for probing the electronic response of solids to extremely strong electric fields localized down to nanometre-sized areas. With ion transmission times in the order of femtoseconds, we can directly probe the local electronic dynamics of an ultrathin foil on this timescale. Here we report on the ability of freestanding single layer graphene to provide tens of electrons for charge neutralization of a slow highly charged ion within a few femtoseconds. With values higher than 10(12) A cm(-2), the resulting local current density in graphene exceeds previously measured breakdown currents by three orders of magnitude. Surprisingly, the passing ion does not tear nanometre-sized holes into the single layer graphene. We use time-dependent density functional theory to gain insight into the multielectron dynamics.
|
|
Kalashnyk N., Khemliche H., & Roncin P. (2016). Atom beam triangulation of organic layers at 100 meV normal energy:self-assembled perylene on Ag(1 1 0) at room temperature. Appl. Surf. Sci., 364, 235–240.
Résumé: The controlled growth of organic layers on surfaces is still waiting for an in-situ reliable technique thatwould allow their quality to be monitored and improved. Here we show that the growth of a perylene monolayer deposited on Ag(110) at room temperature can be tracked with low energy atoms in a regime where the energy perpendicular to the layer is less than 0.1 eV and below the organic film damage threshold. The image processing required for this atom triangulation technique is described in detail.
|
|
Le Moal, E., Marguet, S., Canneson, D., Rogez, B., Boer-Duchemin, E., Dujardin, G., Teperik, T. V., Marinica, D. C., & Borisov, A. G. (2016). Engineering the emission of light from a scanning tunneling microscope using the plasmonic modes of a nanoparticle. Phys. Rev. B, 93(3), 035418.
Résumé: The inelastic tunnel current in the junction formed between the tip of a scanning tunneling microscope (STM) and the sample can electrically generate optical signals. This phenomenon is potentially of great importance for nano-optoelectronic devices. In practice, however, the properties of the emitted light are difficult to control because of the strong influence of the STM tip. In this work, we show both theoretically and experimentally that the sought-after, well-controlled emission of light from an STM tunnel junction may be achieved using a nonplasmonic STM tip and a plasmonic nanoparticle on a transparent substrate. We demonstrate that the native plasmon modes of the nanoparticle may be used to engineer the light emitted in the substrate. Both the angular distribution and intensity of the emitted light may be varied in a predictable way by choosing the excitation position of the STM tip on the particle.
|
|
Marinica, D. - C., Aizpurua, J., & Borisov, A. G. (2016). Quantum effects in the plasmon response of bimetallic core-shell nanostructures. Opt. Express, 24(21), 23941–23956.
Résumé: We report a quantum mechanical study of the plasmonic response of bimetallic spherical core/shell nanoparticles. The systems comprise up to 10<sup>4</sup> electrons and their optical response is addressed with Time Dependent Density Functional Theory calculations. These quantum results are compared with classical electromagnetic calculations for core/shell systems formed by Al/Na, Al/Au and Ag/Na, as representative examples of bimetallic systems. We show that for shell widths in the nanometer range, the system cannot be described as a simple stack of two metals. The finite size effect and the transition layer formed between the core and the shell strongly modify the optical properties of the compound nanoparticle. In particular this configuration leads to a frequency shift of the plasmon resonance with shell character and an increased plasmon decay into electron-hole pairs which eventually quenches this resonance for very thin shells. This effect is difficult to capture with a classical theory even upon adjustment of the parameters of a combination of metallic dielectric functions.
|
|
|
Poumellec, B., Lancry, M., Desmarchelier, R., Hervé, E., & Bourguignon, B. (2016). Parity violation in chiral structure creation under femtosecond laser irradiation in silica glass? Light. Sci. Appl., 5(11), e16178.
|
|
Rogez, B., Cao, S., Dujardin, G., Comtet, G., Le Moal, E., Mayne, A. J., & Boer-Duchemin, E. (2016). The mechanism of light emission from a scanning tunnelling microscope operating in air. Nanotechnology, 27(46), 465201.
Résumé: The scanning tunnelling microscope (STM) may be used as a low-energy, electrical nanosource of surface plasmon polaritons and light. In this article, we demonstrate that the optimum mode of operation of the STM for maximum photon emission is completely different in air than in vacuum. To this end, we investigate the emission of photons, the variation in the relative tip-sample distance and the measured current as a function of time for an STM operating in air. Contrary to the case of an STM operating in vacuum, the measured current between the tip and sample for an STM in air is very unstable (rapidly fluctuating in time) when the applied voltage between the tip and sample is in the ∼1.5–3 V range (i.e., in the energy range of visible photons). The photon emission occurs in short (50 μs) bursts when the STM tip is closest to the sample. The current instabilities are shown to be a key ingredient for producing intense light emission from an STM operating in air (photon emission rate several orders of magnitude higher than for stable current). These results are explained in terms of the interplay between the tunnel current and the electrochemical current in the ubiquitous thin water layer that exists when working in air.
|
|
Sonnet, P., Stauffer, L., Gille, M., Bléger, D., Hecht, S., Cejas, C., Dujardin, G., & Mayne, A. J. (2016). Molecular dissociation on the SiC(0001)-3x3 surface. ChemPhysChem, 17(23), 3900–3906.
Résumé: In the framework of density functional theory, the adsorption of the halogenated polycyclic aromatic hydrocarbon 2,11-diiodohexabenzocoronene (HBC-I2) on the SiC(0001) 3×3 surface has been investigated. Nondissociative and dissociative molecular adsorption is considered, and simulated scanning tunneling microscopy (STM) images are compared with the corresponding experimental observations. Calculations show that dissociative adsorption is favorable and reveal the crucial importance of the extended flat carbon core on molecule–surface interactions in dissociative adsorption; the iodine atom–surface interaction is of minor importance. Indeed, removing iodine atoms does not significantly affect the STM images of the central part of the molecule. This study shows that the dissociation of large halogenated polycyclic aromatic hydrocarbon molecules can occur on the SiC surface. This opens up interesting perspectives in the chemical reactivity and functionalization of wide band gap semiconductors.
|
|
|
Teperik, T. V., Kazansky, A. K., & Borisov, A. G. (2016). Electron tunneling through water layer in nanogaps probed by plasmon resonances. Phys. Rev. B, 93(15), 155431.
|
|
Thon, R., Chin, W., Chamma, D., Galaup, J. - P., Ouvrard, A., Bourguignon, B., & Crépin, C. (2016). Vibrational spectroscopy and dynamics of W(CO)6in solid methane as a probe of lattice properties. J. Chem. Phys., 145(21), 214306.
Résumé: Methane solids present more than one accessible crystalline phase at low temperature at zero pressure. We trap W(CO)6 in CH4 and CD4 matrices between 8 and 35 K to probe the interaction between an impurity and its surrounding molecular solid under various physical conditions. Linear and nonlinear vibrational spectroscopies of W(CO)6 highlight different kinds of interaction and reveal new and remarkable signatures of the phase transition of methane. The structures in the absorption band of the antisymmetric CO stretching mode exhibit a clear modification at the transition between phase II and phase I in CH4 and motional narrowing is observed upon temperature increase. The vibrational dynamics of this mode is probed in stimulated photon echo experiments performed with a femtosecond IR laser. A short component around 10 ps is detected in the population relaxation lifetime in the high temperature phase of solid CH4 (phase I) and disappears at lower temperatures (phase II) where the vibrational lifetime is in the hundreds of ps. The analysis of the nonlinear time-resolved results suggests that the short component comes from a fast energy transfer between the vibrational excitation of the guest and the lattice in specific families of sites. Such fast transfers are observed in the case of W(CO)6 trapped in CD4 because of an energy overlap of the excitation of W(CO)6 and a lattice vibron. In solid CH4, even when these V-V transfers are not efficient, pure dephasing processes due to the molecular nature of the host occur: they are temperature dependent without a clear modification at the phase transition.
|
|
Zapata Herrera, M., Aizpurua, J., Kazansky, A. K., & Borisov, A. G. (2016). Plasmon Response and Electron Dynamics in Charged Metallic Nanoparticles. Langmuir, 32(11), 2829–2840.
Résumé: Using the time-dependent density functional theory, we perform quantum calculations of the electron dynamics in small charged metallic nanoparticles (clusters) of spherical geometry. We show that the excess charge is accumulated at the surface of the nanoparticle within a narrow layer given by the typical screening distance of the electronic system. As a consequence, for nanoparticles in vacuum, the dipolar plasmon mode displays only a small frequency shift upon charging. We obtain a blue shift for positively charged clusters and a red shift for negatively charged clusters, consistent with the change of the electron spill-out from the nanoparticle boundaries. For negatively charged clusters, the Fermi level is eventually promoted above the vacuum level leading to the decay of the excess charge via resonant electron transfer into the continuum. We show that, depending on the charge, the process of electron loss can be very fast, on the femtosecond time scale. Our results are of great relevance to correctly interpret the optical response of the nanoparticles obtained in electrochemistry, and demonstrate that the measured shift of the plasmon resonances upon charging of nanoparticles cannot be explained without account for the surface chemistry and the dielectric environment.
|
|
Zhu, W., Esteban, R., Borisov, A. G., Baumberg, J. J., Nordlander, P., Lezec, H. J., Aizpurua, J., & Crozier, K. B. (2016). Quantum mechanical effects in plasmonic structures with subnanometre gaps. Nat. Commun., 7, 11495.
Résumé: Metallic structures with nanogap features have proven highly effective as building blocks for plasmonic systems, as they can provide a wide tuning range of operating frequencies and large near-field enhancements. Recent work has shown that quantum mechanical effects such as electron tunnelling and nonlocal screening become important as the gap distances approach the subnanometre length-scale. Such quantum effects challenge the classical picture of nanogap plasmons and have stimulated a number of theoretical and experimental studies. This review outlines the findings of many groups into quantum mechanical effects in nanogap plasmons, and discusses outstanding challenges and future directions.
|
|
Actes de Conférences |
Cao, S., Lequeux, M., Le Moal, E., Drezet, A., Huant, S., Dujardin, G., Boer-Duchemin, E. (2016). Using a plasmonic lens to control the emission of electrically excited light. In PROCEEDINGS OF SPIE (Vol. 9884, 98841Y).
Résumé: A local, low-energy, electrical method for the excitation of localized and propagating surface plasmon polaritons (SPPs) is attractive for both fundamental and applied research. In particular, such a method produces no excitation background light and may be integrated with nanoelectronics. Here we report on the electrical excitation of SPPs through the inelastic tunneling of low-energy electrons from the tip of a scanning tunneling microscope (STM) to the surface of a two-dimensional plasmonic lens. The plasmonic structure is a series of concentric circular slits etched in a thick gold film on a glass substrate. An out-going circular SPP wave is generated from the tip-sample junction and is scattered into light by the slits. We compare the resulting emission pattern to that observed when exciting SPPs on a thin, unstructured gold film. For optimized parameters, the light emitted from the plasmonic lens is radially polarized. We describe the effects of the slit period and number, and lens diameter on the emission pattern and we diskuss how the light beam of low divergence is formed.
|
|
