Quantum fluctuations of D5dD_{5d} polarons on C60C_{60} molecules

The dynamic Jahn-Teller splitting of the six equivalent $D_{5d}$ polarons due to quantum fluctuations is studied in the framework of the Bogoliubov-de Gennes formalism. The tunneling induced level splittings are determined to be $^2 T_{1u} \bigoplus ^2 T_{2u}$ and $^1 A_g \bigoplus ^1 H_g$ for $C_{60}^{1-}$ and $C_{60}^{2-}$, respectively, which should give rise to observable effects in experiments.Comment: REVTEX 3.0, 13 pages, to be published in Phys. Rev.

Lattice modes and plasmonic linewidth engineering in gold and aluminum nanoparticle arrays

International audienceLattice modes have been proposed as a means to engineer and control the linewidth and spectral position of optical resonances in arrays of metallic nanoparticles sustaining localized surface plasmon (LSP) resonances. Lattice modes are produced by the interference of LSP-enhanced in-plane scattered light, leading to a Fano-like lineshape with reduced linewidth. In this paper, we study the lattice modes supported by gold and aluminium nanoparticle arrays in the visible and UV, both experimentally and theoretically. The measured and simulated dispersion curves allow us to comprehensively analyze the details of the LSP coupling in the array. We show that when the spectral position of the Rayleigh anomaly, which depends on the period of the array, is slightly blue-shifted with respect to the LSP resonance, the quality factor in the nanoparticle array is significantly increased. We also provide evidence that the formation for the lattice modes, i.e. the coupling between LSPs and the in-plane scattered light, critically depends on the incident light polarization, the coupling efficiency being maximum when the polarization direction is perpendicular to the propagation direction of the grazing wave. The results obtained provide design rules allowing high quality factor resonances throughout visible and ultraviolet spectral ranges, needed for sensing and active nanophotonic applications