Silver nanoparticles deposited on dielectric surfaces

Surface plasmon polaritons in nanoparticles were used as a sensitive indicator of structural and electronic properties of metallic nanoparticles deposited upon various dielectric substrates. Quantum size and cluster-substrate interactions were separated. The latter were modelled with the dynamic charge transfer effect. For calibration purposes, the free surfaces of the same clusters exposed to a UHV beam were also investigated. The particles were slightly deformed during deposition; their final shapes and, in particular, their contact areas were determined. The width of the plasmon excitation band was roughly doubled compared to that of the free particles, but proved to depend only slightly on the chemical nature of the substrates, in drastic contrast to the case of fully embedded particles. The analogy holds for the dephasing lifetimes. One reason for this is that the contact area varies strongly with the substrate material, while it is constant in systems of matrix-embedded particles.