EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

The measurement of acoustic vibrational modes is fundamental to the full comprehension of the mechanical properties of nano-objects, since they are connected to the intrinsic characteristics of the material, such as crystallinity, size, shape and elasticity. At the nanoscale, when localized plasmons couple to localized vibrations, the enhancement of inelastic light scattering signals from acoustic vibrational modes is expected. In this contribution, we investigate the coupling between plasmon and acoustic vibrations of assemblies of 100 nm Au nanocubes using low-frequency Raman spectroscopy. We show that changes in incident polarization affect the plasmon and thus modify the distribution of the electrical field inside the particles, therefore modifying the efficiency of the scattering by the acoustic vibrational modes. We also analyze the polarization of the scattered light for a given incident polarization as a way to correlate the behavior of the vibrational modes to the plasmon modes. We are able to observe a symmetric response of the vibrational modes related to the excited plasmon modes. The acoustic modes detected experimentally are identified with the help of numerical simulations representing vibrational and plasmon modes.