F Javier Garcia de Abajo

Publications (2)17.38 Total impact

• Article: Plasmon spectroscopy and imaging of individual gold nanodecahedra: a combined optical microscopy, cathodoluminescence, and electron energy-loss spectroscopy study.

  Viktor Myroshnychenko, Jaysen Nelayah, Giorgio Adamo, Nicolas Geuquet, Jessica Rodríguez-Fernández, Isabel Pastoriza-Santos, Kevin F MacDonald, Luc Henrard, Luis M Liz-Marzán, Nikolay I Zheludev, Mathieu Kociak, F Javier García de Abajo
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  ABSTRACT: Imaging localized plasmon modes in noble-metal nanoparticles is of fundamental importance for applications such as ultrasensitive molecular detection. Here, we demonstrate the combined use of optical dark-field microscopy (DFM), cathodoluminescence (CL), and electron energy-loss spectroscopy (EELS) to study localized surface plasmons on individual gold nanodecahedra. By exciting surface plasmons with either external light or an electron beam, we experimentally resolve a prominent dipole-active plasmon band in the far-field radiation acquired via DFM and CL, whereas EELS reveals an additional plasmon mode associated with a weak dipole moment. We present measured spectra and intensity maps of plasmon modes in individual nanodecahedra in excellent agreement with boundary-element method simulations, including the effect of the substrate. A simple tight-binding model is formulated to successfully explain the rich plasmon structure in these particles encompasing bright and dark modes, which we predict to be fully observable in less lossy silver decahedra. Our work provides useful insight into the complex nature of plasmon resonances in nanoparticles with pentagonal symmetry.
  Nano Letters 06/2012; 12(8):4172-80. · 13.20 Impact Factor
• Article: Surface plasmon mapping of dumbbell-shaped gold nanorods: the effect of silver coating.

  Benito Rodríguez-González, Farah Attouchi, M Fernanda Cardinal, Viktor Myroshnychenko, Odile Stéphan, F Javier García de Abajo, Luis M Liz-Marzán, Mathieu Kociak
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  ABSTRACT: We report on the identification of surface plasmons in individual gold dumbbell-shaped nanoparticles (AuDBs), as well as AuDBs coated with silver. We use spatially resolved electron energy-loss spectroscopy in a scanning electron microscope, which allows us to map plasmon-energy and intensity spatial distributions. Two dominant plasmon resonances are experimentally resolved in both AuDBs and silver-coated AuDBs. The intensity of these features is peaked either at the tips or at the sides of the nanoparticles. We present boundary element method simulations in good agreement with the experiment, allowing us to elucidate the nature of such modes. While the lower-energy, tip-focused plasmon is of longitudinal character for all dumbbells under consideration, the second side-bound plasmon has a more involved symmetry, starting as a longitudinal quadrupole in homogeneous AuDBs and picking up transversal components when silver coating is added. The longitudinal dipolar mode energy is found to blue-shift upon coating with silver. We find that the substrate produces sizable shifts in the plasmons of silver-coated AuDBs. Our analysis portraits a complex plasmonic scenario in metal nanoparticles coated with silver, including a transition from the original homogeneous gold dumbbell plasmons to the modes of homogeneous silver rods. We believe that these findings can have potential application to plasmon engineering.
  Langmuir 03/2012; 28(24):9063-70. · 4.19 Impact Factor