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Optoelectronics Instrumentation and Data Processing

Resonance energy transfer between a spherical nanoparticle and a J-Aggregate

Alexander A. Zabolotskii

Published May 1, 2017• 5 citations
Publisher

Abstract

This paper describes the nonradiation (Forster) energy transfer between a dye J-aggregate and closely located nanoparticles possessing the properties of two-level systems. Nanoparticles can be quantum dots (QDs) or a spherical symmetric package of atoms. The dynamics of the process is described by deriving the equations that characterize the density matrix dynamics in a two-level medium and the evolution of exciton pulses in an extended quasi-one-dimensional dye J-aggregate. It is shown that effective controlled resonant transfer of the energy stored in QDs is implemented in the system and manifested in the amplification of the exciton pulses. In turn, there is a possibility of the reverse process of exciton energy transfer in partial inversion of two-level transitions of QDs. The results of this paper are confirmed by the experimental data from the literature.

DOI
10.3103/s8756699017030116

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This paper describes the nonradiation (Forster) energy transfer between a dye J-aggregate and closely located nanoparticles possessing the properties of two-level systems. Nanoparticles can be quantum dots (QDs) or a spherical symmetric package of atoms. The dynamics of the process is described by deriving the equations that characterize the density matrix dynamics in a two-level medium and the evolution of exciton pulses in an extended quasi-one-dimensional dye J-aggregate. It is shown that effective controlled resonant transfer of the energy stored in QDs is implemented in the system and manifested in the amplification of the exciton pulses. In turn, there is a possibility of the reverse process of exciton energy transfer in partial inversion of two-level transitions of QDs. The results of this paper are confirmed by the experimental data from the literature.
This paper considers a thin plane nanosystem consisting of molecular chains of dye J-aggregates forming bundles elongated in one direction and spherical gold nanoparticles located near them. Expressions are derived for the polarization of the exciton transition in the external field under the mutual influence of the dipole fields of the monomers constituting the dye J-aggregates and for the induced dipole of the nanoparticle. It is shown that in this system, mirrorless optical bistability of the fluorescence spectral density of the dye J-aggregates is possible, depending on the pump field intensity. The parameters of this dependence are critically determined by the distance between the molecular bundles and nanoparticles and by the angle between the field polarization direction and the axis of the bundle of J-aggregates. The use of the nanosystem as a sensor is discussed.
We study the dynamics of excitonic states in one dimensional, dimer and trimer, and two dimensional arrangements of colloidal quantum dots using a density-matrix approach.The dots are coupled via a dipole-dipole interaction akin to the Förster mechanism.Coherent oscillations of tuned donor dots are shown to appear as plateaus in the acceptor dots, and therefore in their optical response.This behavior provides one with an interesting and unique handle to monitor the quantum state of clusters in an eavesdroping arrangement.A trimer cluster in a symmetrical loop shows steady states in a shorter characteristic time than the typical radiative lifetime of the dots.Breaking the symmetry of the loop results again in damping oscillatory states in the donor dots and plateaus in the eavesdropping/acceptor dot.The use of realistic parameters allows direct comparison with recent experiments and indicates that coherent state monitoring is possible in real experiments.Estimates of the Förster coupling V F are obtained from a microscopic description of the exciton levels in the quantum dot.We present results for different materials CdS, CdSe, GaAs, and InP as function of dot features.V F shows a nonmonotonic variation with dot sizes and a maximum value that depends on the specific dot sizes, material parameters, and dot separation.We also study the effect of the orientation factor on coherent energy transfer from a donor quantum dot to an acceptor quantum dot by calculating the polarization of the acceptor dot.We study how the measurement of the ac-ceptor polarization can be used to determine the relative orientation between the donor-acceptor pair.We also find that Förster coupling between dots results in a polarization memory transfer.
The theory of coherent energy transfer in nanocrystal (NC) systems is generalised for multi-exciton states. We study the effect of the Forster coupling between two individual semiconductor nanocrystals on the pump and induced Rabi oscillations (ROs). The relevant excitonic states in an isolated NC can be described by an effective four-state system, consisting of the ground state, the exciton state, the biexciton state and the triexciton state. The dynamics of a single donor-acceptor pair is described using a density matrix approach that incorporates dipole coupling to multi-exciton states. Our study shows that for short pulse the multi-exciton states play an important role in the dynamics. We also show that the amplitude and the period of the ROs in both dots are heavily influenced by Forster coupling strength. The quality factor of the induced ROs in the acceptor yields information on the energy transfer rate between the two dots. We present result for a variety of sample materials and realistic structure parameters.
A system of excitons in two quantum dots coupled by the dipole–dipole interaction is investigated. The excitation transfer process controlled by the optical Stark effect at nonresonant frequencies is considered and the effect of the interaction between excitons and acoustic phonons in a medium on this process is taken into account. The system evolution is described using quantum Heisenberg equations. A truncated set of equations is obtained and the transfer dynamics is numerically simulated. High-efficiency picosecond switching of the excitation transfer by a laser pulse with a rectangular envelope is demonstrated. The dependence of picosecond switching on the quantum-dot parameters and optical-pulse length is presented.
Specific features of the formation of local fields in spherical composite nanoparticles containing metal cores surrounded by a silica shell with implanted dye molecules are studied. A system consisting of two closely located nanoparticles (dimers) is analyzed. It is shown that the field configuration in the dimer corresponds to a much more effective feedback than that in the case of individual spherical nanoparticles. The dynamics of the fluorescence field near a flat package of composite nanoparticles is studied numerically with due allowance for the enhancement of the dye fluorescence field, saturation of the energetic transition, and diffraction. It is found that close arrangement of nanoparticles leads under pumping conditions to the formation of high-intensity fields localized with time in the space of the nanoparticle package neighborhood.
We study the potential for controlled population inversion in a coupled system comprised of a semiconductor quantum dot and a metal nanoparticle. We show that the widely used method of population inversion by a $\ensuremath{\pi}$ pulse can be modified for small interparticle distances. This modification depends strongly on the pulse duration. We also present analytical solutions of the nonlinear density matrix equations, for specific pulse envelopes, which lead to efficient excitonic population inversion in the quantum dot for several distances between the semiconductor quantum dot and the metal nanoparticle.