From silver nanolentils to nanocolumns: surface plasmon-polaritons and confined acoustic vibrations

Optical and vibrational properties of silver nanolentils, nanospheres, and nanocolumns are studied experimentally using optical transmission spectroscopy and low-frequency Raman scattering. The split of the surface plasmon-polariton resonance into transverse and longitudinal components due to the squeezing or to the elongation of the nanospheres is clearly observed. The vibration band frequencies are demonstrated to be strongly related to the average in-plane diameter, while the quadrupolar vibration modes observed depend on the shape of the nanoparticles.