A comparison of SERS and MEF of rhodamine 6G on a gold substrate

Abstract

Rhodamine 6G is spin-cast onto gold surfaces and the reflectance, emission, excitation, and SERS spectra are reported. Electron microscopy shows that the particle sizes of the gold are uniform for all preparations. Reflection spectra show that the Rh6G aggregates for thicker films and that the gold plasmon band shifts due to the refractive index change on the surface. The intensity of the SERS spectra increases with increasing surface coverage but the rate of change modulates between submonolayer and multilayer surface densities. The emission spectra behave unexpectedly as a function of Rh6G coverage. At submonolayer coverage the emission is relatively strong, decreases as the surface density increases to a monolayer, and then increases as the Rh6G thickness increases. Excitation spectra demonstrate that the emitting species at low surface density is monomeric but for thicker layers the excited state responsible for emission is Rh6G aggregates. For the thicker films, the Rh6G acts as its own dielectric layer for metal enhanced fluorescence of the aggregates.iii ACKNOWLEDGMENTS

Influence of Fano resonance on SERS enhancement in Fano-plasmonic oligomers

“…The resulting SERS spectra are presented in Fig. 7 and they are consistent with the existing literature [53,54,[64][65][66][67]. The SERS spectrum of R6G shows also the N -H in-plane bend mode around 1312 cm -1 in addition to the targeted C -C vibrational stretching at 1363 cm -1 .…”

Luminescence and sensitivity enhancement of oxygen sensors through tuning the spectral overlap between luminescent dyes and SiO2@Ag nanoparticles

“…The higher sensitivity and enhancement of fluorescence intensity of MEF-based oxygen sensors can be mainly attributed to the augmentation of emission due to local field enhancement effects and the increased emission rate by surface plasmon coupled emission, which can increase both the quantum yield and the fluorescence intensity. [15][16][17] The local surface plasmon resonance (LSPR) coupled fluorescence enhancement is a complicated process and impacted by a variety of parameters, including sizes and morphologies of the metal nanoparticles (NPs) and dyes, [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33] distance between the metal surface and the dye, [19,20] maximum spectral overlap of the metal LSPR with the excitation spectra and no overlap with emission spectra of the dye. [21] As previous reported by Ozturk, [14] when the absorbance spectra of noble metal NPs overlap with the emission spectra of dyes, the light emitted by the dyes can be re-absorbed by the noble metal NPs, a process called the inner filter effect, resulting in decreased luminescence density.…”

Gold nanostructures for the sensing of pH using a smartphone

“…leading to applications in sensing. [43][44][45][46][47][48][49] In the present case, Rh-6G was used as a uorescence probe to study the change in its emission behavior in the presence of GNs of different shape and sizes. Rh-6G is a cationic dye belonging to the family of Xanthene dyes 40 and it shows high photostability, high quantum yield, is less prone to photobleaching 41 and provides emission and absorption in the long visible wavelength region, which enhance its probability to have spectral overlap between its absorption spectrum and the emission spectrum of GNs.…”