Spectroscopic properties of Na clusters embedded in a rare-gas matrix

Abstract

International audienc

Matrix effects on the optical response of silver nanoclusters

“…On the theoretical part, recent work by Gervais et al 18 has shown that the surrounding matrix modifies slightly the geometry of the embedded cluster and therefore its electronic structure, changing its optical response. Moreover the presence of the matrix produces a confinement of the valence electrons of the cluster resulting in a blueshift of the transitions.…”

“…This has been observed, for example, in Ag 2 and Ag 3 . [15][16][17] Using quantum calculations on sodium clusters embedded in an argon matrix, Gervais et al 18,19 showed the possible coexistence of several site isomers with slightly different transition energies and intensities. The effect of the matrix is shown to be the result of two competing effects: the dielectric effect discussed above that leads to a redshift and a confinement of the valence electrons of the cluster leading to a blueshift.…”

Ultraviolet-visible absorption of small silver clusters in neon: Agn (n = 1–9)

“…5 The effect of the matrix induces small changes in the geometrical structure of embedding clusters, which may have a large influence on the oscillator strength of the different transitions. 10,43,44 Also symmetry forbidden transitions may be lifted by interaction with the matrix, we suggest that this is the case for Ag 4 and Ag 6 clusters in an argon matrix. The delocalized nature of the conduction electrons leads to isomers of close ground state energies.…”

“…We thus expect that different isomers are present in the matrix. Furthermore, the cluster stabilization energy differs from one matrix to the other 43,44 suggesting that the relative weight of different isomers depends on the embedding matrix. A detailed analysis indicates that these effects are present in the case of Ag 6 , Ag 8 , and Ag 9 clusters.…”

“…Comparison between the argon and neon results shows that the purely dielectric effect 4 has to be refined. Gervais et al 43,44 showed that the effect of the matrix is the result of two competing effects, the Pauli repulsion on one side and the long range polarization of the matrix on the other side. These competing effects may lead to a shift depending, for a given isomer, on the observed transition.…”