Applications of fluorescence from the second excited electronic level of rhodamine 6G

Galanin, M. D.; Chizhikova, Z. A.

doi:10.1007/bf00662486

Cited by 7 publications

(7 citation statements)

References 2 publications

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“…For the calculation, an exciton lifetime of 10 ns was assumed. 19,99,100 There are also higher values found in literature, 87,88,101 but it seems that these values have not been corrected for the reabsorption effect. 100 However, the estimated experimental diffusion constants 102 are considerably lower than our calculated ones.…”

Section: B Anthracenementioning

confidence: 67%

Anisotropy of singlet exciton diffusion in organic semiconductor crystals from ab initio approaches

Stehr

Engels

Deibel

et al. 2014

The Journal of Chemical Physics

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Due to its importance for the function of organic optoelectronic devices, accurate simulations of the singlet exciton diffusion are crucial to predict the performance of new materials. We present a protocol which allows for the efficient directional analysis of exciton transport with high-level ab initio methods. It is based on an alternative to the frequently employed rate equation since the latter was found to be erroneous in some cases. The new approach can be used in combination with the master equation which is considerably faster than the corresponding Monte Carlo approach. The long-range character of the singlet exciton coupling is taken into account by an extrapolation scheme. The approach is applied to singlet exciton diffusion in those substances where these quantities are experimentally best established: naphthalene and anthracene. The high quality of the crystals, furthermore, diminish uncertainties arising from the geometrical structures used in the computations. For those systems, our new approach provides exciton diffusion lengths L for naphthalene and anthracene crystals which show an excellent agreement with their experimental counterparts. For anthracene, for example, the computed L value in a direction is computed to 58 nm while the experimental value is 60 ± 10 nm.

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Section: B Anthracenementioning

confidence: 67%

Anisotropy of singlet exciton diffusion in organic semiconductor crystals from ab initio approaches

Stehr

Engels

Deibel

et al. 2014

The Journal of Chemical Physics

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“…In order to compare the differences for the different quantum chemical methods used for the coupling, Figure shows the diffusion length L in the ( ab ) plane, assuming an exciton lifetime of 78 ns. − The reorganization energy is λ = 347 meV (SCS-CC2/cc-pVTZ) for all calculations. As already seen in Table , SCS-CC2 and SCS-ADC(2) lead to similar results, while TDHF leads to larger diffusion lengths.…”

Section: Results and Discussionmentioning

confidence: 99%

Singlet Exciton Diffusion in Organic Crystals Based on Marcus Transfer Rates

Stehr

Fink

Engels

et al. 2014

J. Chem. Theory Comput.

102

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Exciton diffusion is a critical step for energy conversion in optoelectronic devices. This spawns the desire for theoretical approaches that allow for fast but reliable determinations of the material-dependent exciton transport parameters. For this purpose, the Marcus theory, which is widely used in the context of charge transport, is adapted to exciton diffusion. In contrast to the common approach of calculating the exciton hopping rate via the coupling and the spectral overlap, this alternative approach is less costly, because, instead of the spectral overlap, only the reorganization energy is needed. To demonstrate the capability of the approach, the diffusion constants for naphthalene, anthracene, and diindenoperylene crystals are calculated and compared with both calculations conducted with the well-established exciton hopping rate, including coupling and spectral overlap, and with experimental data. These test calculations show that Marcus-based exciton diffusion properties tend to be too small but are qualitatively correct (i.e., they seem to be useful to predict trends). Nevertheless, for reliable results, high-level quantum chemical approaches are necessary for the computation of the reorganization energies. However, they have to be calculated only once. Coupling constants, which are needed for all pairs of monomers, have a considerably smaller influence, i.e., they can be computed by a lower level approach, which makes the method even less costly.

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“…To ascertain that it is the targeted S n state being excited and that no impurities intervene, a two-step excitation has been suggested. 30 The first laser pulse transfers the system to the S 1 state, and the second pulse, with energy corresponding to the S 1 → S n transition with or without delay, provides additional quanta for exciting the system to exactly the needed S n state. This method allows determining the quantum yield of S n emission.…”

Section: Problems In the Studies Of Anti-kasha Effectsmentioning

confidence: 99%

Breaking the Kasha Rule for More Efficient Photochemistry

2017

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This paper provides a systematic review and analysis of different phenomena that violate a basic principle, Kasha's rule, when applied to photochemical reactions. In contrast to the classical route of ultrafast transition to the lowest energy excited state and photochemical reaction starting therein, in some cases, these reactions proceed directly from high-energy excited states. Nowadays, this phenomenon can be observed for a number of major types of excited-state reactions: harvesting product via intersystem crossing; photoisomerizations; bond-breaking; and electron, proton, and energy transfers. We show that specific conditions for their observation are determined by kinetic factors. They should be among the fastest reactions in studied systems, competing with vibrational relaxation and radiative or nonradiative processes occurring in upper excited states. The anti-Kasha effects, which provide an important element that sheds light on the mechanisms of excited-state transformations, open new possibilities of selective control of these reactions for a variety of practical applications. Efficient utilization of excess electronic energy should enhance performance in the systems of artificial photosynthesis and photovoltaic devices. The modulation of the reporting signal by the energy of excitation of light should lead to new technologies in optical sensing and imaging.

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Applications of fluorescence from the second excited electronic level of rhodamine 6G

Cited by 7 publications

References 2 publications

Anisotropy of singlet exciton diffusion in organic semiconductor crystals from ab initio approaches

Anisotropy of singlet exciton diffusion in organic semiconductor crystals from ab initio approaches

Singlet Exciton Diffusion in Organic Crystals Based on Marcus Transfer Rates

Breaking the Kasha Rule for More Efficient Photochemistry

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