Fluorescence Studies of the Interplay between Metal-Enhanced Fluorescence and Graphene-Induced Quenching

Abstract

Fluorescence microscopy and spectroscopy were applied for studying the optical properties of a hybrid nanostructure, in which we combine plasmon-induced metal enhanced fluorescence with energy transfer to epitaxial graphene. Covering the layer of silver islands with a monolayer graphene, while turning on the efficient energy transfer from emitters, only moderately affects the enhancement of fluorescence attributed to the plasmon resonance in metallic nanostructures-as evidenced by the analysis of fluorescence decays. The results show that it is feasible to combine the properties of graphene with metal-enhanced fluorescence. The importance of the layer thickness of the emitters is also pointed out.

Keywords: energy transfer; graphene; metal-enhanced fluorescence; silver island film.

Figure 1

Fluorescence imaging of three studied structures composed of PCP complexes deposited on (a) Silver Island Film on glass; (b) Single-Double layer graphene on glass; and (c) Single-Double layer graphene transferred on Silver Island Film. For each structure we show a typical fluorescence map and corresponding intensity histogram obtained with the excitation at 480 nm. The intensity scale is the same for all fluorescence images.

Figure 2

Fluorescence intensity histograms obtained from 10 maps measured for each studied sample: PCP on SIF (red), PCP on SDG (black), and PCP on SDG@SIF (blue). The excitation wavelength was 480 nm.

Figure 3

Fluorescence spectra measured for PCP on SIF (red), PCP on SDG (black), and PCP on SDG@SIF (blue). In addition the spectrum measured for PCP on glass is shown in green. The excitation wavelength was 485 nm.

Figure 4

Examples of fluorescence decay curves and histograms of fitted decay times for each fo the investigated samples: (a) PCP on glass (green); (b) PCP on SIF (red); (c) PCP on SDG (black); and (d) PCP on SDG@SIF (black). The excitation wavelength was 485 nm.

Figure 5

Correlation plot showing fluorescence intensities of PCP emission obtained by integrating all measured transient curves as a function of decay times fitted to these transients. Data for PCP on SIF (red), PCP on SDG (black), and PCP on SDG@SIF (blue) are shown. The excitation wavelength was 485 nm.