Regensburg 2000 – wissenschaftliches Programm

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O: Oberflächenphysik

O 11: Postersession (Eröffnung)

O 11.151: Poster

Montag, 27. März 2000, 19:00–22:00, Bereich C

Surface plasmon excitations of metallic spheres in or close to contact — •Andreas Pack und Reinhold Wannemacher — Institut fuer Physik, Universitaet Chemnitz, D-09107 Chemnitz

We have calculated, in a fully retarded, self-consistent calculation and using the standard local dielectric function of different metals, the optical scattering and extinction spectra of aggregates of metallic spheres excited either by plane waves or by the evanescent field generated by total internal reflection. For very small spheres in contact with each other the calculation does not converge even for very high multipole order (>30) due to the large field gradients involved in the problem. In particular, this demonstrates the inapplicability of the frequently employed dipole-dipole approximation for aggregates of particles with sizes in the Rayleigh limit, and is in accord with previous findings from non-retarded calculations. We have mapped out the multipole orders required for convergence of the local calculation as a function of particle size and interparticle distance. Preliminary nonlocal results will be presented.