Ultrafast measurements on direct photoinduced electron transfer in a mixed-valence complex

Walker, Gilbert C.; Barbara, Paul F.; Doorn, Stephen K.; Dong, Yuhua; Hupp, Joseph T.

doi:10.1021/j100168a002

Cited by 125 publications

(77 citation statements)

References 2 publications

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“…11,43,45,46 This drastic reduction in the fluorescence lifetimes has been ascribed to the intermolecular ET from the electron-donating solvents to the excited (S 1 ) coumarin dyes by analogy to a similar type of reaction for Nile blue and oxazine-1 in AN and DMA. 41,45 For the latter two dyes, the reaction products, namely, the radical cations of the solvents and the neutral radicals of the dyes, have been observed by subpicosecond transient absorption measurements. 41,45 The ET rate constants for the present systems are considered to be just the inverse of the fluorescence lifetimes of the dyes in the electron-donating solvents.…”

Section: Methodsmentioning

confidence: 99%

“…[37][38][39][40] A number of examples of ultrafast intermolecular ET between the electron-donating solvents [aniline (AN) and N,N-dimethylaniline (DMA)] and the excited (S 1 ) dyes have been observed by us. 11,22,23,[41][42][43][44][45][46] In all of these cases, the above-mentioned ET theory cannot explain the rates observed. To explain these ultrafast ET dynamics, we have invoked the two-dimensional (solvent and nuclear coordinate) ET model (2D-ET model) [47][48][49] along with its extension by incorporating the participation of a high-frequency vibrational mode, especially of the product state.…”

Section: Introductionmentioning

confidence: 92%

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Deuterium Isotope Effect on Ultrafast Intermolecular Electron Transfer

et al. 1996

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Deuterium isotope effects on ultrafast intermolecular electron transfer (ET) from electron-donating solvents such as aniline (AN) and N,N-dimethylaniline (DMA) to a number of excited (S 1 ) coumarin dyes have been investigated by a femtosecond fluorescence up-conversion technique. We carry out investigations using both normal and deuterated solvents and normal and deuterated coumarin dyes. With perdeuterated AN (AN-d 7 ) or amino-deuterated AN (AN-d 2 ), we observe almost the same extent of reduction in the ET rate constants as in normal AN. In the case of DMA, we do not observe any isotope effect upon substituting all of the N-methyl group hydrogens by deuterium (DMA-d 6 ). Using deuterated coumarins, where the 7-amino group hydrogens are substituted by deuterium, we do not observe any change in the ET dynamics. The effect of isotopic substitution of AN on the ET dynamics has been discussed in terms of the several ET parameters. Cyclic voltammetric measurements indicated that the isotopic substitution of the solvent AN causes a reduction in the driving force for the ET processes. It is inferred that the differences in the driving force for the normal and the deuterated AN as the donor solvent mainly arise from the solvent structural effects, caused by the intermolecular hydrogen bonding in this solvent. The present results also correlate well with the theoretical predictions of the two-dimensional ET model.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 92%

Deuterium Isotope Effect on Ultrafast Intermolecular Electron Transfer

et al. 1996

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“…viridis. [1][2][3][4][5][6][7][8]15,16 This approach can also be applied to current experiments on back electron transfer in mixed-valence compounds, [61][62][63][64][65][66][67][68] where ⌬Ӎ2500 cm Ϫ1 . In this work we study a fast electron transfer process ͑the reaction is almost activationless͒ in a slow relaxation bath in the spin-boson model described by Eq.…”

Section: ͑11͒mentioning

confidence: 99%

“…54-56 and 58 were interested in the thermodynamic properties of the frozen bath approximation when the kinetic energy of the bath mode was neglected; Coalson 57,59 studied dynamics in a spectroscopic problem with a bath described by a set of oscillators, and Evans et al 60 explained experiments on photoinduced electron transfer in mixed-valence compounds. [61][62][63][64][65][66][67][68] However, for the nonadiabatic reactions there is a rigorous approach based on an analysis of the problem in the framework of the spin-boson Hamiltonian, [69][70][71] …”

Section: Introductionmentioning

confidence: 99%

Electron transfer in a slow relaxation bath: Coherence and nonexponential kinetics

Hornbach

Dakhnovskii

1999

The Journal of Chemical Physics

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Effect of the solvent density and species on the back-electron transfer rate in the hexamethylbenzene/tetracyanoethylene charge-transfer complex A fast reaction of an electron transfer in a slow relaxation environment is considered. In the framework of the spin-boson approach, the time-dependent probability, P(t), is shown to be essentially nonexponential at short times. P(t) exhibits coherent oscillations of the electron density with rather different types of decay, depending on the parameter values. The fast decay corresponds to large values of the reaction heat and small values of the transition matrix element. The slow decay, determined by P(t)Ӎcos(⌬t)/ͱt, corresponds to large values of the electronic matrix element and small barriers. The general expression for P(t) is interpreted as free coherent oscillations of the electron density. The heat of the reaction is treated as a random Gaussian variable centered at the value ⑀ϪE r , where ⑀ and E r are the bias and reorganization energy, respectively. It is pointed out that such nonexponential behavior can be observed for fast reactions in matrices of inert gases or electron transfer in bacterial photosynthetic centers or photoexcited mixed-valence compounds.

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“…[22][23][24][25][26][27][28][29][30][31][32][33][34][35][36] In most but not all cases, asymmetric systems were in focus in which -owing either to two different redox centres or to an asymmetric bridging moiety -the two diabatic states possess different Gibbs energies. [22][23][24][25][26][27][28][29][30][31][32][33][34][35][36] In most but not all cases, asymmetric systems were in focus in which -owing either to two different redox centres or to an asymmetric bridging moiety -the two diabatic states possess different Gibbs energies.…”

Section: Introductionmentioning

confidence: 99%

How fast is optically induced electron transfer in organic mixed valence systems?

Lambert

Moos

Schmiedel

et al. 2016

Phys. Chem. Chem. Phys.

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The rate of thermally induced electron transfer in organic mixed valence compounds has thoroughly been investigated by e.g. temperature dependent ESR spectroscopy. However, almost nothing is known about the dynamics of optically induced electron transfer processes in such systems. Therefore, we investigated these processes in mixed valence compounds based on triphenylamine redox centres bridged by conjugated spacers by NIR transient absorption spectroscopy with fs-time resolution. These experiments revealed an internal conversion (IC) process to be on the order of 50-200 fs which is equivalent to the back electron transfer after optical excitation into the intervalence charge transfer band. This IC is followed by ultrafast cooling to the ground state within 1 ps. Thus, in the systems investigated optically induced electron transfer is about 3-4 orders of magnitude faster than thermally induced ET.

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Ultrafast measurements on direct photoinduced electron transfer in a mixed-valence complex

Cited by 125 publications

References 2 publications

Deuterium Isotope Effect on Ultrafast Intermolecular Electron Transfer

Deuterium Isotope Effect on Ultrafast Intermolecular Electron Transfer

Electron transfer in a slow relaxation bath: Coherence and nonexponential kinetics

How fast is optically induced electron transfer in organic mixed valence systems?

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