Experimental evidence of nanometer-scale confinement of plasmonic eigenmodes responsible for hot spots in random metallic films

Arthur Losquin (1) , Sophie Camelio (2) , David Rossouw (3) , Mondher Besbes (4) , Frédéric Pailloux (2) , David Babonneau (2) , Gianluigi A. Botton (3) , Jean-Jacques Greffet (4) , Odile Stéphan (1) , Mathieu Kociak (1)

1 LPS - Laboratoire de Physique des Solides
2 PPrime [Poitiers] - Institut Pprime [UPR 3346]
3 Department of Materials Science and Engineering, McMaster University
4 Laboratoire Charles Fabry / Naphel

We report on the identification and nanometer scale characterization over a large energy range of random, disorder-driven, surface plasmons in silver semicontinuous films embedded in silicon nitride. By performing spatially resolved electron energy loss spectroscopy experiments, we experimentally demonstrate that these plasmons eigenmodes arise when the films become fractal, leading to the emergence of strong electrical fields (" hot spots ") localized over few nanometers. We show that disorder-driven surface plasmons strongly depart from those usually found in nanoparticles, being strongly confined and randomly and densely distributed in space and energy. Beyond that, we show that they have no obvious relation with the local morphology of the films, in stark contrast with surface plasmon eigenmodes of nanoparticles.

Domains: Optics [physics.optics]

Arthur Losquin, Sophie Camelio, David Rossouw, Mondher Besbes, Frédéric Pailloux, et al.. Experimental evidence of nanometer-scale confinement of plasmonic eigenmodes responsible for hot spots in random metallic films. Physical Review B: Condensed Matter and Materials Physics (1998-2015), 2013, 88 (11), pp.115427. ⟨10.1103/PhysRevB.88.115427⟩. ⟨hal-01335075⟩