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Nano-optics

Scientific highlights

Plasmonic quantum size effects in silver nanoparticles are dominated by interfaces and local environments

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The physical properties of metals change when their dimensions are reduced to the nano-scale and new phenomena such as the localized surface plasmon resonance (LSPR) appear. This collective electronic excitation can be tuned over a large spectral range by adapting the material, size and shape. The existing literature is as rich as it is controversial—for example, size-dependent spectral shifts of the LSPR in small metal nanoparticles, induced by quantum effects, are reported to the red, to the blue or entirely absent. Here we report how complementary experiments on size-selected small silver nanoparticles embedded in silica can yield inconsistent results on the same system: whereas optical absorption shows no size effect in the range between only a few atoms and ~10 nm, a clear spectral shift is observed in single-particle electron spectroscopy. Our quantitative interpretation, based on a mixed classical/quantum model, resolves the apparent contradictions, not only within our experimental data but also in the literature. Our comprehensive model describes how the local environment is the crucial parameter controlling the manifestation or absence of quantum size effects. Read more »

Optical gap and optically active intragap defects in cubic BN

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Studies on the optical properties of cubic BN are generally hindered by the very high density of crystal defects. Thus, the precise value of its optical gap is still debated, with large discrepancies between reported theoretical and experimental estimated values. In this study we addressed open questions of the cubic BN optics by employing high spatially resolved spectroscopy techniques to the highest-quality samples available and combining these observations with state-of-the-art quasiparticle calculations.

Phys. Rev. B 98, 094106 (2018)

Publications

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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