Wednesday, October 10, 2012

1210.2535 (Søren Raza et al.)

Blueshift of the surface plasmon resonance in silver nanoparticles
studied with EELS
   [PDF]

Søren Raza, Nicolas Stenger, Shima Kadkhodazadeh, Søren V. Fischer, Natalie Kostesha, Antti-Pekka Jauho, Andrew Burrows, Martijn Wubs, N. Asger Mortensen
We study the surface plasmon (SP) resonance energy of isolated spherical Ag nanoparticles in the diameter range 3.5-26 nm with monochromated electron energy-loss spectroscopy. A significant blueshift of the SP resonance energy of 0.5 eV is measured when the particle size decreases from 26 down to 3.5 nm. We interpret the observed blueshift using three models for a metallic sphere embedded in homogeneous background material: a classical Drude model with a homogeneous electron density profile in the metal, a semiclassical model corrected for an inhomogeneous electron density associated with quantum confinement, and a semiclassical nonlocal hydrodynamic description of the electron density. We find that the latter two models provide a qualitative explanation for the observed blueshift, but the theoretical predictions show smaller blueshifts than observed experimentally. We attribute the larger measured blueshift to effects due to the presence of the substrate, which breaks the symmetry of a particle embedded in a homogeneous medium.
View original: http://arxiv.org/abs/1210.2535

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