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Nano-optics

Scientific highlights

Tailored nanoscale plasmon-enhanced vibrational electron spectroscopy

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Atomic vibrations and phonons are an excellent source of information on nanomaterials that we can access through a variety of methods including Raman Scattering, infrared spectroscopy, and electron energy-loss spectroscopy (EELS). In the presence of a plasmon local field, vibrations are strongly modified, and in particular, their dipolar strengths are highly enhanced, thus rendering Raman scattering and infrared spectroscopy extremely sensitive techniques. Here, we experimentally demonstrate that the interacion between a relativistic electron and vibrational modes in nanostructures is fundamentally modified in the presence of plasmons. We finely tune the energy of surface plasmons in metallic nanowires in the vicinity of hexagonal boron nitride, making it possible to monitor and disentangle both strong phonon-plasmon coupling and plasmon-driven phonon enhancement at the nanometer scale. Due to the near-field character of the electron beam-phonon interaction, optically-inactive phonon modes are also observed. Read more »

Emergence of point defect states in a plasmonic crystal

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Plasmonic crystals are well known to have band structure including a band gap, enabling the control of surface plasmon propagation and confinement. The band dispersion relation of bulk crystals has been generally measured by momentum-resolved spectroscopy using far field optical techniques while the defects introduced in the crystals have separately been investigated by near field imaging techniques so far. Particularly, defect related energy levels introduced in the plasmonic band gap have not been observed experimentally. In order to investigate such a localized mode, we performed electron energy-loss spectroscopy (EELS) on a point defect introduced in a plasmonic crystal made up of flat cylinders protruding out of a metal film and arranged on a triangular lattice. The energy level of the defect mode was observed to lie within the full band-gap energy range. This was confirmed by a momentum-resolved EELS measurement of the band gap performed on the same plasmonic crystal. Read more »

Publications

Rodríguez-González, B., et al. Surface Plasmon Mapping of Dumbbell-Shaped Gold Nanorods: The Effect of Silver Coating. Langmuir 120410144721001 (2012).doi:10.1021/la300269n Download: la300269n.pdf (4.19 MB)
Tourbot, G., et al. Growth mechanism and properties of InGaN insertions in GaN nanowires. Nanotechnology 23, 135703 (2012). Download: Nanotechnology 2012 Tourbot.pdf (802.75 KB)
Mazzucco, S., et al. Ultralocal Modification of Surface Plasmons Properties in Silver Nanocubes. Nano Letters 120202105244000 (2012).doi:10.1021/nl2037672 Download: Nano Lett. 2012 Mazzucco.pdf (3.49 MB)
Kociak, M. & de Abajo, F.J.G. Nanoscale mapping of plasmons, photons, and excitons. MRS Bulletin 37, 39 - 46 (2012). Download: MRS Bull. 2012 Kociak-1.pdf (1.01 MB)
Mazzucco, S., et al. Spatially resolved measurements of plasmonic eigenstates in complex-shaped, asymmetric nanoparticles: gold nanostars. The European Physical Journal Applied Physics 54, 33512 (2011). Download: Eur. Phys. J. Appl. Phys. 2011 Mazzucco.pdf (3 MB)
Boudarham, G., et al. Spectral Imaging of Individual Split-Ring Resonators. Physical Review Letters 105, 255501 (2010). Download: Phys. Rev. Lett. 2010 Boudarham.pdf (567.25 KB)
de Abajo, F.J.G., Asenjo-Garcia, A. & Kociak, M. Multiphoton Absorption and Emission by Interaction of Swift Electrons with Evanescent Light Fields. Nano Letters 10, 1859–1863 (2010).
Nelayah, J., et al. Two-Dimensional Quasistatic Stationary Short Range Surface Plasmons in Flat Nanoprisms. Nano Letters 10, 902–907 (2010). Download: Nano Lett. 2010 Nelayah.pdf (2.58 MB)
Arenal, R., et al. Optical gap measurements on individual boron nitride nanotubes by electron energy loss spectroscopy. Microscopy And Microanalysis 14, 274–282 (2008).
de Abajo, F.J.G. & Kociak, M. Probing the Photonic Local Density of States with Electron Energy Loss Spectroscopy. Physical Review Letters 100, 106804 (2008). Download: Phys. Rev. Lett. 2008 García de Abajo.pdf (540.82 KB)
Nelayah, J., et al. Mapping surface plasmons on a single metallic nanoparticle. Nature Physics 3, 348–353 (2007). Download: Nat Phys 2007 Nelayah.pdf (676.34 KB)
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