Plasmon-enhanced fluorescence of submonolayer porphyrins by silver-polymer core-shell nanoparticles

Abstract

We investigate the fluorescence from submonolayer porphyrin molecules near silver-polymer core-shell nanoparticles (NPs) at a well-controlled separation distance of about 1 nm - 5 nm. When porphyrin molecules are deposited on silver NPs with the plasmonic resonance peak at about 410 nm, which matches very closely with the 405-nm excitation laser and the absorption band of porphyrin molecules, their emission intensity is found to be enhanced due to the plasmonic resonant excitation enhancement, and shows a decline as the increasing polymer shell thickness. Meanwhile, the lifetime results demonstrate that there exists the fluorescence quenching due to the charge transfer and nonradiative energy transfer losses, which is also the main reason that the maximum enhancement factor obtained in experiment is only about 2.3, although the theoretical one is above 60 according to the electric field distribution near silver NPs calculated by finite-difference time-domain method.

Extraordinary Fluorescence Enhancement in Metal-Dielectric Core–Shell Nanoparticles

“…Metal-dielectric core–shell nanoparticles − ,,− offer an opportunity to engineer environments where the various competing considerations described above are balanced or optimized for particular applications. They are moreover attractive for a number of applications as they may be produced with low-cost chemical synthesis methods in large quantities.…”

Critical Role of Shell in Enhanced Fluorescence of Metal–Dielectric Core–Shell Nanoparticles

“…For Ag and Au shells, this translates into a whole visible and near-infrared range simply by the control of a core–shell morphology, i.e., of the ratio r c / r s . ,,, In the dielectric shell case, the tunability limits are set between Re ε c = −2ε h for r s → r c and Re ε c = −2ε s for r c → 0, and the resulting tunability is narrower and typically of the order of ∼100 nm. For the same reason, an initial search for fluorescence enhancement focused more on metal shell particles, whereas the use of metal–dielectric core–shell particles, apart from some preliminary work, ,,− still remains to be underestimated in the current literature.…”

Distance-Dependent Plasmon-Enhanced Fluorescence of Submonolayer Rhodamine 6G by Gold Nanoparticles

“…The thickness of poly (methyl methacrylate) (PMMA) separating layer could be precisely controlled to tune the emission properties of single quantum dots [ 40 ]. Tetraphenyl porphyrin (TPP) molecules have been demonstrated to be affected dramatically by the localized plasmon mode [ 41 , 42 ].…”