We used a confocal laser microscope to investigate the one-photon photoluminescence (PL) of gold antennas. The PL spectra can precisely be fitted to a plasmon enhanced photoluminescence model. For increasing antenna length, the energy peak position decreases continuously until it reaches a value of 1.7 – 1.8 eV. For longer antennas and smaller plasmon energies, we observe an additional, persistent shoulder in the PL spectra, which we explain by a Gaussian-shaped peak at ~1.78 – 1.79 eV. We attribute this behavior to the opening of an additional decay path for electrons at the gold interband transition edge which we observe only for long antennas.
(a) Schematics of the PL measurements. (b) PL spectrum and its Lorentzian fit as an example. Here, the power P of the incident laser was 500 mW. (c) SEM image of the corresponding gold antenna whose geometrical values (length aSEM and width bSEM) are determined as indicated by the yellow lines. |
Additional peak appearing in the one-photon luminescence of single gold nanorods
Toni Froehlich, Christian Schönenberger, and Michel Calame
Optics Letters 41(7) 1325-1328 (2016)