Complexes

Fluorescence spectroscopy is applied to study the influence of plasmon excitations in spherical Au nanoparticles on the optical properties of chlorophyll-containing light-harvesting complexes. The separation between the two nanostructures is controlled via silica layer with varied thickness. We observe strong increase of the emission intensity for a 12-nm-thick spacer and the increase is accompanied with shortening of the fluorescence lifetime, which allows us to sepa-rate contributions of absorption and emission rate enhancement. At the same time we find an increase of photobleaching. These findings are interpreted as a result of spectral overlap between plasmon resonance and chlorophyll fluorescence