Low wavenumber Raman scattering of cobalt nanoparticles self‐organized in 3D superlattices far from surface plasmon resonance

Abstract

We report the first observation of low wavenumber Raman scattering from cobalt nanoparticles under 514.5nm laser excitation. These 7.4nm diameter particles were self‐organized in 3D superlattices, but we assign the Raman signature to vibrations of the individual nanoparticles, according to Lamb's elastic sphere model. We estimate the relative Raman intensity to be around 500 times lower than it would be for silver nanoparticles, but our results demonstrate that surface plasmon–phonon resonance coupling is not mandatory to observe Lamb's modes in metal nanoparticles. Copyright © 2015 John Wiley & Sons, Ltd.