Theory of Transition–Dipole Coupling in Dye-Sensitized Semiconductor Nanoparticles

Zweigle, Greg; McHale, Jeanne L.

doi:10.1021/jp1122954

Cited by 6 publications

(7 citation statements)

References 36 publications

(60 reference statements)

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“…It has been observed that the emission intensity increases approximately 10-fold as the dye molecules deposited on ZnO nanoparticle surface. In the presence of ZnO nanoparticles, the emission spectrum is slightly red-shifted; this can be contributed to the electronic coupling of the fluorophore and electronic states of the semiconductor [ 36 ].…”

Section: Resultsmentioning

confidence: 99%

Photophysical Behaviors of Single Fluorophores Localized on Zinc Oxide Nanostructures

Zhang

Lakowicz

2012

IJMS

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Single-molecule fluorescence spectroscopy has now been widely used to investigate complex dynamic processes which would normally be obscured in an ensemble-averaged measurement. In this report we studied photophysical behaviors of single fluorophores in proximity to zinc oxide nanostructures by single-molecule fluorescence spectroscopy and time-correlated single-photon counting (TCSPC). Single fluorophores on ZnO surfaces showed enhanced fluorescence brightness to various extents compared with those on glass; the single-molecule time trajectories also illustrated pronounced fluctuations of emission intensities, with time periods distributed from milliseconds to seconds. We attribute fluorescence fluctuations to the interfacial electron transfer (ET) events. The fluorescence fluctuation dynamics were found to be inhomogeneous from molecule to molecule and from time to time, showing significant static and dynamic disorders in the interfacial electron transfer reaction processes.

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Section: Resultsmentioning

confidence: 99%

Photophysical Behaviors of Single Fluorophores Localized on Zinc Oxide Nanostructures

Zhang

Lakowicz

2012

IJMS

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“…Red-shifted spectra of dyes on TiO 2 relative to solution are common and result from electronic coupling of the dye and TiO 2 . 58 Because a spectral blue shift of Bt on TiO 2 could also result from partial oxidation of Bt under room lights, we examined the spectra of Bt on ZrO 2 . The observation of a similar blue shift for Bt on ZrO 2 at high dye loadings shows that the blue shift does not result from oxidation ( Figure S1).…”

Section: ■ Discussionmentioning

confidence: 99%

Dynamics of Interfacial Electron Transfer from Betanin to Nanocrystalline TiO₂: The Pursuit of Two-Electron Injection

et al. 2015

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We report spectroelectrochemical and transient absorption spectroscopic studies of electron injection from the plant pigment betanin (Bt) to nanocrystalline TiO 2 . Spectroelectrochemical experiments and density functional theory (DFT) calculations are used to interpret transient absorption data in terms of excited state absorption of Bt and ground state absorption of oxidation intermediates and products. Comparison of the amplitudes of transient signals of Bt on TiO 2 and on ZrO 2 , for which no electron injection takes place, reveals the signature of two-electron injection from electronically excited Bt to TiO 2 . Transient signals observed for Bt on TiO 2 (in contrast to ZrO 2 ) on the nanosecond time scale reveal the spectral signatures of photo-oxidation products of Bt absorbing in the red and the blue. These are assigned to a oneelectron oxidation product formed by recombination of injected electrons with the two-electron oxidation product. We conclude that whereas electron injection is a simultaneous two-electron process, recombination is a one-electron process. The formation of a semiquinone radical through recombination limits the efficiency and long-term stability of the Bt-based dye-sensitized solar cell. Strategies are suggested for enhancing photocurrents of dye-sensitized solar cells by harnessing the two-electron oxidation of organic dye sensitizers.

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“…Note also that (20b) and (20c) involve the product of three resonances: one at ε K = 0, one at ε 0 = 0 and the third, in brackets, is a logarithmic resonance 12,14,28 at the Fermi level ε F = 0. In a previous work, we showed that experimental SERS excitation profiles could be fit to Fano profiles, 24 and the current derivation places that work on a sound theoretical foundation.…”

Section: Derivation Of Polarizability In Molecule-metal Systemsmentioning

confidence: 99%

The theory of surface-enhanced Raman scattering

Lombardi

Birke

2012

The Journal of Chemical Physics

132

103

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By considering the molecule and metal to form a conjoined system, we derive an expression for the observed Raman spectrum in surface-enhanced Raman scattering. The metal levels are considered to consist of a continuum with levels filled up to the Fermi level, and empty above, while the molecule has discrete levels filled up to the highest occupied orbital, and empty above that. It is presumed that the Fermi level of the metal lies between the highest filled and the lowest unfilled level of the molecule. The molecule levels are then coupled to the metal continuum both in the filled and unfilled levels, and using the solutions to this problem provided by Fano, we derive an expression for the transition amplitude between the ground stationary state and some excited stationary state of the molecule-metal system. It is shown that three resonances contribute to the overall enhancement; namely, the surface plasmon resonance, the molecular resonances, as well as charge-transfer resonances between the molecule and metal. Furthermore, these resonances are linked by terms in the numerator, which result in SERS selection rules. These linked resonances cannot be separated, accounting for many of the observed SERS phenomena. The molecule-metal coupling is interpreted in terms of a deformation potential which is compared to the Herzberg-Teller vibronic coupling constant. We show that one term in the sum involves coupling between the surface plasmon transition dipole and the molecular transition dipole. They are coupled through the deformation potential connecting to charge-transfer states. Another term is shown to involve coupling between the charge-transfer transition and the molecular transition dipoles. These are coupled by the deformation potential connecting to plasmon resonance states. By applying the selection rules to the cases of dimer and trimer nanoparticles we show that the SERS spectrum can vary considerably with excitation wavelength, depending on which plasmon and/or charge-transfer resonance is excited.

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Theory of Transition–Dipole Coupling in Dye-Sensitized Semiconductor Nanoparticles

Cited by 6 publications

References 36 publications

Photophysical Behaviors of Single Fluorophores Localized on Zinc Oxide Nanostructures

Photophysical Behaviors of Single Fluorophores Localized on Zinc Oxide Nanostructures

Dynamics of Interfacial Electron Transfer from Betanin to Nanocrystalline TiO₂: The Pursuit of Two-Electron Injection

The theory of surface-enhanced Raman scattering

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Theory of Transition–Dipole Coupling in Dye-Sensitized Semiconductor Nanoparticles

Cited by 6 publications

References 36 publications

Photophysical Behaviors of Single Fluorophores Localized on Zinc Oxide Nanostructures

Photophysical Behaviors of Single Fluorophores Localized on Zinc Oxide Nanostructures

Dynamics of Interfacial Electron Transfer from Betanin to Nanocrystalline TiO2: The Pursuit of Two-Electron Injection

The theory of surface-enhanced Raman scattering

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Dynamics of Interfacial Electron Transfer from Betanin to Nanocrystalline TiO₂: The Pursuit of Two-Electron Injection