Polarizability of truncated spheroidal particles supported by a substrate: model and applications
Laboratoire Mixte CNRS/Saint-Gobain "Surface du Verre et Interfaces"
39, Quai Lucien Lefranc, BP 135, 93303 Aubervilliers Cedex, France
2 Department of Physics, The Norwegian University of Science and Technology, 7491 Trondheim, Norway
3 Leiden Institut of Chemistry, Leiden University PO Box 9502, 2300 RA Leiden, The Netherlands
Corresponding author: a Jacques.Jupille@saint-gobain.com
Revised: 31 July 2001
Published online: 15 November 2001
The light scattering by three-dimensional clusters supported by a substrate is modelled by representing clusters by truncated spheroids whose polarizability is calculated via a multipolar development of the potential in the quasi-static limit. The determination of the mean island radius, density and aspect ratio from the optical response is examined. The strong influence of both the particle-substrate interaction and the particle shape on the optical behaviour is demonstrated, showing the limits of effective medium and dipolar theories. The Surface Differential Reflectance spectra of silver on MgO(100) and titanium or aluminium on α-Al2O3(0001) surfaces have then been modelled by using the above model, illustrating the capability of optical means to deal with various metals, including those belonging to transition series. In all cases, it is highlighted that the aspect ratio is central in modelling the optical response of supported particles.
PACS: 78.20.Bh – Theory, models, and numerical simulation / 73.20.Mf – Collective excitations (including excitons, polarons, plasmons and other charge-density excitations) / 68.55.Ac – Nucleation and growth: microscopic aspects
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2001