Three-Center Systems for Energy Pooling:  Quantum Electrodynamical Theory

Jenkins, Robert D.; Andrews, Davıd L.

doi:10.1021/jp983071h

Cited by 54 publications

(57 citation statements)

References 42 publications

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“…As shown in earlier work based on molecular QED 15,16 the results emerge, from fourth-order time-dependent perturbation theory, in the form of the following rate equation;…”

Section: Cooperative and Accretive Transfer: Energy Pooling Processesmentioning

confidence: 62%

Electronic coupling mechanisms and characteristics for optically nonlinear photoactive nanomaterials

Andrews

2004

SPIE Proceedings

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In a range of nanophotonic energy harvesting materials, resonance energy transfer (RET) is the mechanism for the intermolecular and intramolecular transfer of electronic excitation following the absorption of ultraviolet/visible radiation. In the nonlinear intensity regime, suitably designed materials can exhibit two quite different types of mechanism for channeling the excitation energy to an acceptor that is optically transparent at the input frequency. Both mechanisms are associated with two-photon optical excitation -of either a single donor, or a pair of donor chromophores, located close to the acceptor. In the former case the mechanism is two-photon resonance energy transfer, initiated by two-photon absorption at a donor, and followed by RET directly to the acceptor. The probability for fulfilling the initial conditions for this mechanism (for the donors to exhibit two-photon absorption) is enhanced at high levels of optical input. In the latter twin-donor mechanism, following initial one-photon excitations of two electronically distinct donors, energy pooling results in a collective channeling of their energy to an acceptor chromophore. This mechanism also becomes effective under high intensity conditions due to the enhanced probability of exciting donor chromophores within close proximity of each other and the acceptor. In this paper we describe the detailed balance of factors that determines the favored mechanism for these forms of optical nonlinearity, especially electronic factors. Attention is focused on dendrimeric nanostar materials with a propensity for optical nonlinearity.

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“…As shown in earlier work based on molecular QED 15,16 the results emerge, from fourth-order time-dependent perturbation theory, in the form of the following rate equation;…”

Section: Cooperative and Accretive Transfer: Energy Pooling Processesmentioning

confidence: 62%

Electronic coupling mechanisms and characteristics for optically nonlinear photoactive nanomaterials

Andrews

2004

SPIE Proceedings

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“…As shown in earlier work 12,19 the results emerge from fourth-order perturbation theory in the form of the following rate equation;…”

Section: Twin-donor Energy Pooling Mechanismsmentioning

confidence: 64%

“…26 To estimate the associated effects we can consider that all transition dipole moments and separation vectors are equivalent, and that components of each of the  tensors have similar magnitude to the corresponding polarisability components. Then, it is possible to write the intimidating expression within the final bracket of equation (12) in the greatly simplified form that follows; …”

Section: B Structural Factorsmentioning

confidence: 99%

Nonlinear energy pooling in nanophotonic materials

Andrews¹

2004

SPIE Proceedings

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Recently there has been considerable interest in the construction of photoactive organic materials designed to exhibit novel forms of optical nonlinearity. By exploiting the unique properties of these nanomaterials at high levels of photon flux, new possibilities emerge for applications in energy harvesting, low-threshold lasing, quantum logic devices, photodynamic therapy, etc. In particular, a detailed appraisal of the theory spotlights novel mechanisms for directed energy transfer and energy pooling in nanophotonic dendrimers. Characterized by a nonlinear dependence on the optical irradiance, these mechanisms fall into two classes: (a) those where two-photon absorption by individual donors is followed by transfer of the sum energy to the acceptor; (b) where the excitation of two electronically distinct but neighbouring donor groups is followed by a collective migration of their energy to a suitable acceptor. In each case these transfer processes are subject to minor dissipative losses, associated with intramolecular vibrational relaxation in the donor species. In this paper we describe in detail the balance of factors and the constraints that determines the favored mechanism, which include the excitation statistics, structure of the energy levels, selection rules, molecular architecture, the distribution of donors and acceptors, spectral overlap and coherence factors. Knowledge of these factors and the means for their optimization offers fresh insights into nanophotonic characteristics, and informs strategies for the design of new photoactive materials.

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“…The second mechanism is a twin-donor pooling process [68] which, following initial one-photon excitations of two electronically distinct donors, results in the collective migration of donor energies at the acceptor chromophore: …”

Section: Multiphoton Processesmentioning

confidence: 99%

Mechanisms of Light Energy Harvesting in Dendrimers and Hyperbranched Polymers

Bradshaw

Andrews

2011

Polymers

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Abstract:Since their earliest synthesis, much interest has arisen in the use of dendritic and structurally allied forms of polymer for light energy harvesting, especially as organic adjuncts for solar energy devices. With the facility to accommodate a proliferation of antenna chromophores, such materials can capture and channel light energy with a high degree of efficiency, each polymer unit potentially delivering the energy of one photon-or more, when optical nonlinearity is involved. To ensure the highest efficiency of operation, it is essential to understand the processes responsible for photon capture and channelling of the resulting electronic excitation. Highlighting the latest theoretical advances, this paper reviews the principal mechanisms, which prove to involve a complex interplay of structural, spectroscopic and electrodynamic properties. Designing materials with the capacity to capture and control light energy facilitates applications that now extend from solar energy to medical photonics.

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Three-Center Systems for Energy Pooling: Quantum Electrodynamical Theory

Cited by 54 publications

References 42 publications

Electronic coupling mechanisms and characteristics for optically nonlinear photoactive nanomaterials

Electronic coupling mechanisms and characteristics for optically nonlinear photoactive nanomaterials

Nonlinear energy pooling in nanophotonic materials

Mechanisms of Light Energy Harvesting in Dendrimers and Hyperbranched Polymers

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