title: Competition Between Resonant Plasmonic Coupling and Electrostatic Interaction in Reduced Graphene Oxide Quantum Dots.
abstract: The light emission from reduced graphene oxide quantum dots (rGO-QDs) exhibit a significant enhancement in photoluminescence (PL) due to localized surface plasmon (LSP) interactions. Silver and gold nanoparticles (NPs) coupled to rGO nanoparticles exhibit the effect of resonant LSP coupling on the emission processes. Enhancement of the radiative recombination rate in the presence of Ag-NPs induced LSP tuned to the emission energy results in a four-fold increase in PL intensity. The localized field due to the resonantly coupled LSP modes induces n-π* transitions that are not observed in the absence of the resonant interaction of the plasmons with the excitons. An increase in the density of the Ag-NPs result in a detuning of the LSP energy from the emission energy of the nanoparticles. The detuning is due to the cumulative effect of the red-shift in the LSP energy and the electrostatic field induced blue shift in the PL energy of the rGO-QDs. The detuning quenches the PL emission from rGO-QDs at higher concentration of Ag NPs due to non-dissipative effects unlike plasmon induced Joule heating that occurs under resonance conditions. An increase in Au nanoparticles concentration results in an enhancement of PL emission due to electrostatic image charge effect.
authors.affiliation: Inst. of Fundamental and Frontier Sciences, Univ. of Electronic Science and Technology of China, Chengdu, P.R. China.|Department of Physics, University of North Texas, Denton 76203, USA.|Department of Mechanical and Energy Engineering, University of North Texas, Denton 76207, USA.
authors.forename: Sanjay
authors.initials: S
authors.lastname: Karna
authors.affiliation: Department of Physics, University of North Texas, Denton 76203, USA.
authors.forename: Meg
authors.initials: M
authors.lastname: Mahat
authors.affiliation: Department of Mechanical and Energy Engineering, University of North Texas, Denton 76207, USA.
authors.forename: Tae-Youl
authors.initials: TY
authors.lastname: Choi
authors.affiliation: Department of Mathematical and Physical Sciences, Japan Women's University, Tokyo, 112-8681 Japan.
authors.forename: Ryoko
authors.initials: R
authors.lastname: Shimada
authors.affiliation: Inst. of Fundamental and Frontier Sciences, Univ. of Electronic Science and Technology of China, Chengdu, P.R. China.
authors.forename: Zhiming
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Inst. of Fundamental and Frontier Sciences, Univ. of Electronic Science and Technology of China, Chengdu, P.R. China.|Department of Physics, University of North Texas, Denton 76203, USA.|Advanced Manufacturing and Materials Processing Institute, University of North Texas, Denton Texas, 76207, USA.
authors.forename: Arup
authors.initials: A
authors.lastname: Neogi