Dipole resonances of an ionized cluster

Abstract

We study the resonance properties of an ionized spherical cluster that interacts with an optical radiation field in terms of linear hot-plasma polarizability models. Based on a generalization that includes spatial dispersion in the well-known Mie problem of the diffraction of a plane wave by a small-size plasma sphere, we calculate the eigenfrequencies, the radiative and collisional damping constants, and the resonance amplitudes of the cluster surface and bulk plasmon fields. The role of collisionless dissipation processes is analyzed in terms of a one-dimensional kinetic model. The latter allows the corresponding damping constants for both types of plasmons to be determined as functions of the characteristic electron-plasma boundary collision frequency. We show that both types of plasmons in certain domains of cluster and external-radiation parameters can undergo a strong resonance that causes both the amplitude of the scattered wave and the absorbed power and the field inside the cluster to increase significantly.