Regensburg 2016 – scientific programme

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O: Fachverband Oberflächenphysik

O 52: Photonics and Nanooptics II: Nonlinear Response

O 52.10: Talk

Wednesday, March 9, 2016, 12:45–13:00, S051

Plasmon dynamics on nanoporous gold particles revealed by strong field photoemission — Germann Hergert¹, •Jan Vogelsang¹, Jörg Robin¹, Petra Groß¹, Dong Wang², Peter Schaaf², Erich Runge², and Christoph Lienau¹ — ¹Carl von Ossietzky Universität, Oldenburg, Germany — ²Technische Universität Ilmenau, Ilmenau, Germany

Nanoporous gold particles or ''nanosponges'' are particles with a diameter of hundreds of nanometers, perforated with randomly arranged pores with diameters in the 10-nm range. They have recently attracted attention as templates for surface-enhanced Raman sensing as they combine several advantageous properties, such as multiple plasmon resonances in the visible or NIR spectral range, a high surface-to-volume ratio, and a high density of catalytic sites [1].

Here we investigate the plasmon dynamics of such particles using ultrafast photoemission microscopy. When using 14-fs excitation pulses at 1600 nm for excitation of single nanosponges, we observe long-lived plasmon oscillations as a function of the pulse delay. Introducing a new model for the optical properties of these particles, we show that our results reveal the existence of long-lived plasmon hotspots with lifetimes of several tens of fs on the surface of the sponge. This plasmon localization could be of key importance for enhancing the sensing capability of such particles.

[1] C. Vidal et al, ACS Photonics 2, 1436 (2015)