We show how coherent, spatially resolved spectroscopy can disentangle complex hybrid wave functions into wave functions of the individual emitters. This way, detailed information on the coupling of the individual emitters, not available in far-field spectroscopy, can be revealed. Here we propose a quantum state tomography protocol that relies on the ability to selectively excite each emitter individually by spatially localized pulses. Simulations of coupled semiconductor GaAs/InAs quantum dots using light fields available in current nanoplasmonics show, that undesired resonances can be removed from measured spectra. The method can be applied on a broad range of coupled emitters to study the internal coupling, including pigments in photosynthesis and artificial light harvesting.

A quantum-kinetic approach to the ultrafast dynamics of carrier multiplication in semiconductor quantum dots is presented. We investigate the underlying dynamics in the electronic subband occupations and the time-resolved optical emission spectrum, focusing on the interplay between the light-matter and the Coulomb interaction. We find a transition between qualitatively differing behaviors of carrier multiplication, which is controlled by the ratio of the interaction induced time scale and the pulse duration of the exciting light pulse. On short time scales, i.e., before intraband relaxation, this opens the possibility of detecting carrier multiplication without refering to measurements of (multi-)exciton lifetimes.

Coral Pt islands films are deposited via electrochemical reduction on silica-coated nanostructured Ag electrodes. From these devices surface-enhanced (resonance) Raman [SE(R)R] signals of molecules exclusively attached to Pt are obtained with intensity up to 50% of the value determined for Ag. SE(R)R spectroscopic investigations are carried out with different probe molecules, silica-coating thicknesses, and excitation lines. Additionally, field enhancement calculations on Ag-SiO(2)-Pt support geometries are performed to elucidate the influence of the Pt island film nanostructure on the observed Raman intensities. It is concluded that the nonperfect coating of the Pt island film promotes the efficiency of the induced Pt SER activity. Comparison with similar measurements on Ag-SiO(2)-Au electrodes further suggests that the chemical nature of the deposited metal island film plays a minor role for the SE(R)R intensity.

The homogeneous linewidth of dye aggregates like photosynthetic light-harvesting complexes contains important information about energy transfer and relaxation times that is, however, masked by inhomogeneous broadening caused by static disorder. Whereas there exist line narrowing techniques for the study of low-energy exciton states, the homogeneous linewidth of the high-energy states is not so easy to decipher. Here we present a microscopic theory for nonlinear polarization spectroscopy in the frequency domain that contains a dynamic aggregate selection revealing the homogeneous linewidth of these states. The theory is applied to the water-soluble chlorophyll-binding protein for which the high-energy exciton state was predicted to exhibit a sub-100-fs lifetime.

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