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We have studied the effects of planar, lamellar, and random nanostructured metal-dielectric environments on spontaneous emission and energy transfer concentration quenching of HITC laser dye. We found an inhibition of the concentration quenching in vicinity of metal, which was stronger in nanostructured substrates than in plain geometries. It was shown that the same substrates, which boosted spontaneous emission, also inhibited the concentration quenching. The effect is discussed in terms of the Forster radius affected by losses. Work at LLNL was performed under the auspices of the U.S. Department of Energy by LLNL under Contract DE-AC52-07NA27344

We present the novel metamaterial based on a nanoporous alumina membrane impregnated with R6G dye molecules. The splitting of the reflectance and emission bands at large dye concentration is discussed in terms of strong coupling.

We have studied strong exciton-plasmon coupling in the films of Ag nanoislands as well as in the layer-by-layer (LBL) deposited films of Au nanoparticles (NPs) coated with highly concentrated rhodamine 6G (R6G) dye. Their absorbance and the reflectance spectra featured the peaks or dips, which were not characteristic of dye or NPs/nanoislands taken separately. The positions of the spectral maxima (or minima) in the dye-doped films, plotted against those in pristine Ag nanoislands films, resulted in the dispersion curves comprised of three branches. They could be described by the analytical model based on the Hamiltonian accounting for the unperturbed energies of the surface plasmon (SP) resonance, the two bands composing the absorption spectrum of R6G dye, and the exciton-plasmon coupling energy Δ. Its value was larger in Ag nanoislands films deposited on hyperbolic metamaterials (0.221 eV) than on glass (0.165 eV). The minimal gap between the upper and the lower branches was equal to ≈3Δ. The dispersion curves in the Au NPs LBL films could be described with the Hamiltonian equation at relatively small dye concentrations. At larger concentrations of R6G molecules, the spectral peaks shifted and became more pronounced. The corresponding dispersion curve could not be described in terms of the existing model, indicating the need for further theoretical studies.

We have studied the spectroscopic properties of nanoporous alumina membranes impregnated with rhodamine 6G (R6G) dye molecules. At small dye concentrations, the reflectance spectra feature one minimum, corresponding to the absorption band of R6G. With increase of the dye concentration, the reflectance dip splits in two and the energy difference between the two minima increases. A similar behavior is shared by the emission spectral band. We explain these observations in terms of strong coupling of closely situated dye molecules inside the channels. At the same time, the experimentally observed angular dependence of the reflectance spectrum is consistent with a long-range collective behavior of dye molecules across an array of dye-impregnated channels.

Proximity to metallic surfaces, plasmonic structures, cavities and other inhomogeneous dielectric environments is known to control spontaneous emission, energy transfer, scattering and many other phenomena of practical importance. The aim of the present study was to demonstrate that, in spirit of the Marcus theory, the rates of chemical reactions can, too, be influenced by nonlocal dielectric environments, such as metallic films and metal/dielectric bilayer or multilayer structures. We have experimentally shown that metallic, composite metal/dielectric substrates can, indeed, control ordering as well as photodegradation of thin poly-3-hexylthiophene (p3ht) films. In many particular experiments, p3ht films were separated from metal by a dielectric spacer, excluding conventional catalysis facilitated by metals and making modification of the nonlocal dielectric environment a plausible explanation for the observed phenomena. This first step toward understanding of a complex relationship between chemical reactions and nonlocal dielectric environments is to be followed by the theory development and a broader scope of thorough experimental studies.

We show that photo-oxidation of organic semiconducting films can be controlled by geometry and composition of metallic and metal/dielectric substrates, in agreement with increase of the chemical reaction rate by the density of photonic states.