Friction of the surface plasmon by high-energy particle-hole pairs
Are memory effects important?
Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, 28049 Madrid, Spain
2 Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504 (ULP-CNRS), BP 43, 23 rue du Loess, 67034 Strasbourg Cedex 2, France
3 Institut für Physik, Universität Augsburg, Universitätsstraße 1, 86135 Augsburg, Germany
4 Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
Corresponding author: a email@example.com
Published online: 20 June 2007
We show that the dynamics of the surface plasmon in metallic nanoparticles damped by its interaction with particle-hole excitations can be modelled by a single degree of freedom coupled to an environment. In this approach, the fast decrease of the dipole matrix elements that couple the plasmon to particle-hole pairs with the energy of the excitation allows a separation of the Hilbert space into low- and high-energy subspaces at a characteristic energy that we estimate. A picture of the spectrum consisting of a collective excitation built from low-energy excitations which interacts with high-energy particle-hole states can be formalised. The high-energy excitations yield an approximate description of a dissipative environment (or “bath") within a finite confined system. Estimates for the relevant timescales establish the Markovian character of the bath dynamics with respect to the surface plasmon evolution for nanoparticles with a radius larger than about 1 nm.
PACS: 73.20.Mf – Collective excitations / 71.45.Gm – Exchange, correlation, dielectric and magnetic response functions, plasmons
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2007