Surface plasmon‐enhanced molecular fluorescence induced by gold nanostructures

Abstract

The authors report on surface plasmon-enhanced fluorescence of Eosin Y molecules induced by gold nanostructures. Al 2 O 3 films deposited by atomic layer deposition with sub-nanometer resolution were used as the spacer layer to control the distance between molecules and the gold surface. As the thickness of the Al 2 O 3 film increased, the fluorescence intensity first increased and then decreased. The highest enhancement factor is achieved with a 1 nm Al 2 O 3 film. However, the trend for the fluorescence lifetime is the opposite. It first decreased and then increased. The changes in the fluorescence quantum yield were also calculated. The yield shows a similar trend to the fluorescence intensity. The competition between the surface plasmoninduced increase in the radiative decay rate and the goldinduced fluorescence quenching is responsible for the observed phenomenon. In addition, this competition strongly depends on the thickness of the spacer layer between Eosin Y molecules and the gold surface.

Sweet plasmonics: Sucrose macrocrystals of metal nanoparticles

“…0.75, 1.00, and 2.50 mL Au NP incorporated macrocrystals, which experienced fluorescence quenching, possessed lifetimes of 10.6, 11.6, and 12.6 ns respectively. These observations together with the increase in quantum efficiency can be explained in terms of plasmonic interactions between the QDs and the Au NPs, and the results are strongly parallel to the study of Teng et al [13], where lifetime shortening (lengthening) was observed in the case of plasmonic fluorescence enhancement (quenching) of Eosin Y on gold nanostructures fabricated employing electron beam lithography. In our experiment, only the sample including 0.75 mL of Au NP does not obey the trend indicated above.…”

“…We found out that the increase of the field enhancement factor plays a crucial role in the fluorescence enhancement. On the other hand, the fluorescence quenching was attributed to the decrease of the field enhancement factor below unity, as also reported by Teng et al [13] while the effect of nonradiative energy transfer from CdTe QDs to Au NPs remained weaker. Bearing in mind its simplicity, inexpensiveness, and robustness, we believe that this new composite material may find applications in various fields of science, especially in optics and photonics, requiring solid materials with large dimensions that employ plasmonic interaction.…”

Fabrication of large-area plasmonic nanostructures for surface enhanced fluorescence

“…The inductively coupled plasma source power and the platen power were 1000 W and 4 W, respectively. The flow rates for SF 6 and O 2 were 30.5 sccm and 27.5 sccm, respectively. The etch process had a 7 minutes long temperature stabilization period followed by a 7 minutes long etching step.…”

“…Atomic layer deposition is also utilized to precisely tune the separation between the molecules and the metal structures. [6] It has been found that this separation plays an important role in SEF and has an influence to the quantum yield. However, the above methods require either expensive equipments or tedious processes and the fabrication area is limited, thus they are not well suited for low-cost and high-throughput fabrication.…”

“…[5] This kind of simple structures are suitable to investigate the enhancement mechanism itself, but it is difficult to enable a large-area fabrication with a uniform enhancement. Periodic structures such as an array of nanodots prepared by e-beam lithography [6] gratings prepared by laser interference lithography [7] are ideal candidates to investigate the fundamentals of SEF with a uniform enhancement due to the precise design and the control of the size, shape and alignment of the metal nanostructures. Atomic layer deposition is also utilized to precisely tune the separation between the molecules and the metal structures.…”