Radiative and Nonradiative Rates of Phosphors Attached to Gold Nanoparticles

Abstract

Gold nanoparticles manipulate the quantum efficiency of phosphorescent molecules, which are attached via biotin−streptavidin recognition at a distance of 4 nm to the nanoparticle surface. Time-resolved luminescence spectroscopy reveals an increase in the radiative as well as in the nonradiative rate of the phosphorescent molecules upon binding to gold nanoparticles. The increase in the radiative rate alone would lead to an increased luminescence quantum yield. However, this effect is outweighed by the distinct enhancement of the nonradiative rate due to energy transfer, resulting in an overall quenching of the luminescence.

A Strategy for the Maximum Fluorescence Enhancement Based on Tetrahedral Amorphous Carbon-Coated Metal Substrates

“…This is an indication that the enhancement is due to the near-field coupling between the fluorophore dipole and SP electronic oscillations at the emission frequency. [18][19][20] Since the excitation wavelength (514 nm) is well outside the main plasmon excitation band, we expect a negligible contribution from the absorption enhancement in our experiment. In addition, although time-resolved measurements would be useful to disentangle the contributions of different enhancement pathways, in our case the substrate-dependent enhancement factors and spectral positions of localized SP resonances suggest the involvement of a plasmon-coupled emission mechanism.…”

“…1 Plasmon excitation results in significantly enhanced local electric fields at the nanoparticle surfaces, which gives rise to fundamentally interesting phenomena and technologically important applications [2][3][4][5][6][7][8][9] such as MEF. [10][11][12][13][14][15][16][17] MEF is the modification of the fluorescence intensities and lifetimes for fluorophores placed near a metal surface, [18][19][20] which has attracted special attention from the viewpoints of academic as well as industrial interests. There are two competitive mechanisms at work which are both dependent on the separation distance between the fluorophores and metal surfaces.…”

Fluorescence Enhancement by Au Nanostructures: Nanoshells and Nanorods

“…Table 2 shows that the k nr increases when IR800 is bound to HSA compared to the free fluorophore in solution. On a metallic surface, the nonradiative decay rate also increases for short fluorophoreϪmetal distances, Ͻ4 nm, 35,36 since the nonradiative energy transfer rate depends on the inverse cube of the moleculeϪsurface separation. 35 However, in our nanostructure complexes, HSA provides a spacer layer of ϳ8 nm between the fluorophore and the metal nanoparticle surface.…”

Influence of colloidal-gold films on the luminescence of Eu(TTFA)3 in PMMA

“…Although the observed net effect of the colloidal gold layer is to decrease luminescence lifetimes and quantum efficiencies, it is possible that the radiative relaxation rate constant has also been affected (increased) [2,8,24,31,50]. If so, one would expect I/I 0 4t/ t 0, because the reduction in the value of t would be due partly to an increase in the radiative decay constant.…”