Humboldt-Universität zu Berlin - Mathematisch-Naturwissen­schaft­liche Fakultät - SFB 951 - HIOS

 Colloquium of the SFB 951
'Hybrid Inorganic/Organic Systems for Opto-Electronics'

 

Thursday, October 27, 4 pm
Department of Physics, Humboldt-Universität zu Berlin, Newtonstraße 15, Room 1´201: Christian-Gerthsen-Hörsaal

Nano-Plasmonic systems provide novel ways for controlling the propagation of light and light-matter interaction via large electric field enhancements, strong field gradients, and coupling to non-radiative plasmon modes. In view of the increasing sophistication of fabrication and spectroscopic characterization, quantitative computational approaches face challenges that go well beyond the usual description of metals as linear dispersive materials. These challenges include the development of material models that describe the (potentially) strongly nonlocal and nonlinear optical response of such metallic nano-structures as well as the strongly modified light-matter interaction that is mediated by them.

This talk reports on the progress of applying the recently developed Discontinuous-Galerkin Time-Domain (DGTD) method to the quantitative analysis of nano-plasmonic systems with an emphasis on advanced material models. This includes the efficient modeling of complex geometric features via curvilinear elements, the incorporation of optically anisotropic media, and the determination of electron-energy loss spectra. In addition, this talk reports on recent results regarding the development and application of a hydrodynamic description of the metal’s conduction electrons. By coupling the Maxwell equations to this material model of a plasma in confined geometry one is able to capture nonlocal and nonlinear effects.

It is of particular interest in plasmonics to achieve a detailed understanding of molecule metal-nanoparticle (MNP) interactions and MNP affected transport and optical properties [1]. To attain this goal a microscopic theory is introduced. It focuses on systems with a small spatial extension where the molecule-MNP interaction is dominated by its (instantaneous) Coulomb part. Following [2,3] a description of MNP plasmon excitations is achieved by (i) separating the MNP electron motion into a center of mass (collective) and into a relative motion, and by (ii) introducing this separation into a system-bath description of dissipative quantum dynamics. Related density matrix equations account for a finite plasmon life-time and also offer a non-perturbative consideration of intermolecular and molecule-MNP couplings.

First applications of this approach based on parametrized models are presented. A MNP affected intermolecular excitation energy transfer is considered [4]. Then, emission and absorption spectra of molecular complexes placed in the proximity of a spherical MNP are discussed [5]. Finally, a plasmon enhanced photoinduced switch of the current through a molecular junction is proposed [6].

References: [1] Chem. Rev. 111 (2011) special issue: 2011 Plasmonics; [2] L. G. Gerchikov, C. Guet, and A. N. Ipatov, Phys. Rev. B 66, 053202 (2002); [3] G. Weick, G.-L. Ingold, R. A. Jalabert, and D. Weinmann, Phys. Rev. B 74, 165421 (2006); [4] G. Kyas and V. May, J. Chem. Phys. 134, 034701 (2011); [5] Ya. R. Zelinskyy and V. May, Chem. Phys. Lett. 511, 372 (2011); [6] Ya. R. Zelinskyy and V. May, Phys. Rev. B (submitted).