Ultrafast electron trapping in an aqueous NaCl-solution

Assel, M.; Laenen, R.; Laubereau, A.

doi:10.1016/s0009-2614(98)00415-1

Cited by 44 publications

(33 citation statements)

References 33 publications

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“…Femtosecond pump-probe spectroscopy on various CTTS systems supports the predicted formation of pair species [9][10][11][12][13][14][15][16][17]. The extracted depth of the potential well is typically in the order of a few k B T [15][16][17][18][19].…”

Section: Introductionmentioning

confidence: 68%

Electron detachment from anions in aqueous solutions studied by two- and three-pulse femtosecond spectroscopy

Iglev

Fischer

Laubereau

2010

Pure and Applied Chemistry

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The electron photodetachment of the aqueous halides and hydroxide is studied after resonant excitation in the lowest charge-transfer-to-solvent (CTTS) state. The initially excited state is followed by an intermediate assigned to a donor-electron pair that displays a competition of recombination and separation. Using pump-repump-probe (PREP) spectroscopy, the pair species is verified via a secondary excitation with separation of the pairs so that the yield of released electrons is increased. The observed recombination process on the one hand and the similar absorptions of the intermediate and the hydrated electron on the other hand suggest that the donor-electron pairs incorporate only few if not just one water molecule. The geminate dynamics measured in the various CTTS systems reveal a strong influence of the parent radical. The electron survival probability decreases significantly from 0.77 to 0.29 going from F -to OH -. The extracted dissociation rates of the halogen-electron pairs seem to be proportional to the mutual diffusion coefficients of the geminate particles, while such a relation between the recombination rate and the diffusion coefficient is not found. Results for I -show that excitation of a higher-lying CTTS state opens a new relaxation channel, which directly leads to a fully hydrated electron, while the relaxation channel discussed above is not significantly affected.

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Section: Introductionmentioning

confidence: 68%

Electron detachment from anions in aqueous solutions studied by two- and three-pulse femtosecond spectroscopy

Iglev

Fischer

Laubereau

2010

Pure and Applied Chemistry

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“…Of course, once a 5 M HCl concentration is reached, detachment of the chloride ions by two photons may contribute a significant fraction of the electron population. 35,36 At our excitation intensities, we estimate this effect to be significant only for the iodide-free 5 M HCl solutions. However, because the excitation energy in our experiment ͑9.7 eV͒ considerably exceeds that in Refs.…”

Section: ͑7͒mentioning

confidence: 88%

Time-resolved scavenging and recombination dynamics from I:e− caged pairs

Kloepfer¹,

Vilchiz²,

Lenchenkov³

et al. 2002

The Journal of Chemical Physics

130

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The competition between geminate recombination of electrons with their parent radicals and electron scavenging with H+ is directly time resolved with ∼100 fs resolution at several acid concentrations. Electrons were produced from iodide photodetachment or two-photon ionization of H2O. With regards to those produced from iodide photodetachment, the separation between primary and secondary I:e− recombination is established using a full numerical solution to the diffusion equation. Electron ejection is found to be short range and a potential well of ∼3kbT depth stabilizing the solvent caged pair is required to yield a satisfactory fit to experiment. From time-resolved scavenging data up to 5 M HCl, it is shown that the electron can be scavenged both inside and outside the caged pair by H+ with nearly equal efficiency. The steady-state scavenging yield as a function of scavenger concentration is then predicted based on the determined time-dependent recombination function. Reassessment of several benchmark scavenging experiments from the 1960’s leads to the conclusion that the primary yield of electrons after excitation of iodide is near unity.

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“…The trapping mechanism can be compared for electrons injected into water via a number of different fundamental routes; injection into the conduction band by H 2 O multiphoton photoionization 40,41,[44][45][46][47]50,52 or by anion multiphoton detachment, 18,21,22,92 and injection below the conduction band via ionization of a low ionization potential neutral 49 or via CTTS detachment of an anion. We have observed and directly contrasted the results of electron trapping by detachment of a prototype anion through its lowest CTTS state and by direct ionization of water into the conduction band in this paper.…”

Section: Comparison Of Electron Ejection Mechanismsmentioning

confidence: 99%

“…73 Similar multiphoton detachment experiments have been performed for chloride ions. [20][21][22]92 Unlike the iodide multiphoton case, Gauduel has claimed evidence for the formation of a contact pair as one intermediate before electron escape, however this conclusion was reached not by consideration of the recombination reactions but by including an extra spectral component at 880 nm in a complex kinetic fit containing six distinct absorbing electron species. 21,92 In the more recent work of Assel et al, such a spectral feature was not observed.…”

Section: Comparison Of Electron Ejection Mechanismsmentioning

confidence: 99%

“…18,19 Likewise, the subpicosecond detachment dynamics of aqueous Cl Ϫ has been examined by Gauduel,20,21 and more recently by Laubereau's group. 22 It was the work by Eisenthal and Gauduel that stimulated the detailed theoretical calculations by Rossky and by Staib and Borgis to build a microscopic model for the electron photodetachment process. [9][10][11] However, since multiphoton excitation was used to initiate electron ejection in each of these experiments, questions remain concerning the number of absorbed photons and the nature of the initially prepared state.…”

Section: Introductionmentioning

confidence: 99%

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The ejection distribution of solvated electrons generated by the one-photon photodetachment of aqueous I− and two-photon ionization of the solvent

Kloepfer

Vilchiz

Lenchenkov

et al. 2000

The Journal of Chemical Physics

191

362

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Articles you may be interested inOne-photon photodetachment of I − in glycerol: Spectra and yield of solvated electrons in the temperature range 329 T 536 K Mechanisms of the ultrafast production and recombination of solvated electrons in weakly polar fluids: Comparison of multiphoton ionization and detachment via the charge-transfer-to-solvent transition of Na − in THF The spectra and the relative yield of solvated electrons produced by resonant photodetachment of iodide anion in ethylene glycol in the temperature range 296T453 K Two-photon dissociation and ionization of liquid water studied by femtosecond transient absorption spectroscopyThe ultrafast dynamics following one-photon UV photodetachment of I Ϫ ions in aqueous solution are compared with those following two-photon ionization of the solvent. Ultrafast pump-probe experiments employing 50 fs ultraviolet pulses reveal similar and very rapid time scales for electron ejection. However, the electron ejection process from water pumped into the conduction band and from iodide ions detached at threshold are readily distinguishable. The observed picosecond timescale geminate recombination and electron escape dynamics are reconstructed using two different models, a diffusion-limited return of the electron from ϳ15 Å to its parent and a competing kinetics model governed by the reverse electron transfer rate. We conclude that the ''ejected'' electron in the halide detachment is merely separated from the halogen atom within the same solvent shell. The assignment of detachment into a contact pair is based on the recombination profile rather than by the postulate of any new spectral absorption due to an electron in a contact pair. The contact pair is surprisingly long-lived and the nonadiabatic recombination is rather slow considering the proximity of the partners. Experiments in mixed solvents confirm our assignment of the two distinct ejection mechanisms. The detachment mechanism is therefore fundamentally different in the resonant ͑one photon͒ charge-transfer-to-solvent ͑CTTS͒ process from the multiphoton detachment of aqueous iodide ions, which bears more similarity to the direct solvent ionization.

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Ultrafast electron trapping in an aqueous NaCl-solution

Cited by 44 publications

References 33 publications

Electron detachment from anions in aqueous solutions studied by two- and three-pulse femtosecond spectroscopy

Electron detachment from anions in aqueous solutions studied by two- and three-pulse femtosecond spectroscopy

Time-resolved scavenging and recombination dynamics from I:e− caged pairs

The ejection distribution of solvated electrons generated by the one-photon photodetachment of aqueous I− and two-photon ionization of the solvent

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