Collective Response in DNA-Stabilized Silver Cluster Assemblies from First-Principles Simulations.

We investigate fluorescence resonant energy transfer and concurrent electron dynamics in a pair of DNA-stabilized silver clusters. For this purpose we introduce a methodology for the simulation of collective optoelectronic properties of coupled molecular aggregates starting from first-principles quantum chemistry, which can be further applied to a broad range of coupled molecular systems to study their electro-optical response. Our simulations reveal the existence of low-energy coupled excitonic states, which enable ultrafast energy transport between subunits, and give insight into the origin of the fluorescence signal in coupled DNA-stabilized silver clusters, which have been recently experimentally detected.

Excitonic Properties of Ordered Metal Nanocluster Arrays: 2D Silver Clusters at Multiporphyrin Templates.

The design of ordered arrays of metal nanoclusters such as, for example, two-dimensional cluster-organic frameworks might open a new route toward the development of materials with tailored optical properties. Such systems could serve as plasmonically enhanced light-harvesting materials, sensors, or catalysts. We present here a theoretical approach for the simulation of the optical properties of ordered arrays of metal clusters that is based on the ab initio parametrized Frenkel exciton model.

Excited state nonadiabatic dynamics of bare and hydrated anionic gold clusters Au3(-)[H2O]n (n = 0-2).

We present a joint theoretical and experimental study of excited state dynamics in pure and hydrated anionic gold clusters Au3(-)[H2O]n (n = 0-2). We employ mixed quantum-classical dynamics combined with femtosecond time-resolved photoelectron spectroscopy in order to investigate the influence of hydration on excited state lifetimes and photo-dissociation dynamics. A gradual decrease of the excited state lifetime with the number of adsorbed water molecules as well as gold cluster fragmentation quenching by two or more water molecules are observed both in experiment and in simulations.

Polarization properties of polymer-dispersed liquid-crystal film with small nematic droplets.

The polarization state of light transmitted through a polymer-dispersed liquid-crystal film with small, spherical, nonabsorbing, partially oriented nematic droplets is theoretically investigated. The model used is based on the effective medium approach. Scattering properties of a single droplet are described by the Rayleigh-Gans approximation.