Stable Surface Plasmon Resonances in Small Alumina-Embedded Silver Clusters

Murilo Moreira (1, 2) , Emmanuel Cottancin (2) , Michel Pellarin (2) , Olivier Boisron (2) , Varlei Rodrigues (1) , Jean Lermé (2) , Matthias Hillenkamp (1, 2)

1 IFGW - Instituto de Fisica 'Gleb Wataghin'
2 iLM - AGNANO - iLM - Agrégats et nanostructures

Localized Surface Plasmon Resonances are ubiquitous for the characterization and in applications of noble metal nanoparticles. Their dependence on chemical composition, size, shape and environment is widely studied since decades but still many aspects are subject of controversy. In this article we experimentally investigate surfactant-free and mass-selected silver nanoparticles embedded in alumina matrices in the size range between several atoms and more than 4 nm diameter, spanning the whole range from large nanoparticles, accurately described by classical Mie theory, down into the range of quantum size effects. Strong and stable resonances are observed for all sizes down to less than 50 atoms, i.e. ~1 nm diameter, without significant line shift or broadening as a function of size. With the help of semi-quantal simulations, we identify all signals as surface plasmon resonances. The absence of peak shifts is rationalized as due to the dielectric oxide environment and the constant width of the resonances as a convolution of inhomogeneities in the local environment and inherent broadening due to Landau damping. We discuss our results in comparison to ligand-stabilized nanoclusters and rationalize the different contributions to the Hamiltonian describing the systems.

Mots clés: Surface plasmon resonance; silver clusters; size effects; environment; semiquantal simulations; jellium

Domaines: Physique [physics]

Murilo Moreira, Emmanuel Cottancin, Michel Pellarin, Olivier Boisron, Varlei Rodrigues, et al.. Stable Surface Plasmon Resonances in Small Alumina-Embedded Silver Clusters. Journal of Physical Chemistry C, 2023, 127 (36), pp.17828-17835. ⟨10.1021/acs.jpcc.3c03200⟩. ⟨hal-04214536⟩