Transient spectra, formation, and geminate recombination of solvated electrons in pure water UV-photolysis: an alternative view

Hertwig, Andreas; Hippler, H.; Unterreiner, Andreas‐Neil

doi:10.1039/a906950j

Cited by 55 publications

(94 citation statements)

References 48 publications

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“…The electron appearance time was assigned a time constant ( rise ) of 200 fs for both probe wavelengths. We note that a faster electron appearance time is observed in our experiments with a 900 and 1000 nm probe, however the trapping dynamics are entangled with the overall electron solvation and relaxation 38,72 and thus the timescale for the electron localization in the solvent is faster than 200 fs.…”

Section: A Water Photoionizationmentioning

confidence: 47%

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

194

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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Section: A Water Photoionizationmentioning

confidence: 47%

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

194

362

View full text Add to dashboard Cite

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“…In other words there is a continuous transition from the 'hot' hydrated electron to the wellknown equilibrated hydrated electron. Hertwig, Hippler and Unterreiner [24] demonstrated that the spectrum of the relaxing hydrated electron is blue-shifted during this process with a time constant τ ϭ 300Ϯ50 fs. The assumptions for the simple evaluation of the experimental observations are: The oscillator strength is 1 and the spectra show shape stability [9,25,26].…”

Section: Some Comments On the 'Incompletely Relaxed Electron'mentioning

confidence: 98%

Is there any Correlation between the Mobility and the Absorption Spectra of Solvated Electrons in Polar Solvents?

Krebs¹

2000

Zeitschrift Für Physikalische Chemie

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Some years ago Jay-Gerin and Ferradini attempted to establish a correlation between the optical absorption spectrum and the mobility of excess electrons in various polar solvents (J. Chem. Phys. 91 (1989) 3275). To explain this correlation they postulated two types of electrons, i.e., highly localized solvated electrons and so-called incompletely relaxed electrons. This was done, however, without any physical justification. According to this correlation and its interpretation just the stable ammoniated electron (surprisingly not considered by Jay-Gerin and Ferradini) should be a quite typical representative of these incompletely relaxed electrons. Therefore, we analyzed the theoretical relationship between the electron mobility and the zero-frequency absorption cross section with the aid of the experimentally observed absorption spectra. We found out that there is no support for a linear relationship between the mobility and the position of the maximum, បωmax, of the optical absorption band and that the contribution of the cross section to the electron mobility is practically zero. Therefore, the proposed correlation has no physical background. We show, however, that there exists a rough correlation between the excess electron mobility and the self-diffusion coefficient of the polar solvent. Finally we critically consider the so-called incompletely relaxed electron state and the results of quantum statistical simulations of the diffusion coefficient of solvated electrons (e Ϫ solv ).

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“…[37][38][39]52 and references therein). These ultrafast processes are followed by slower solvent rearrangement (fs to ps timescales) and slow geminate recombination 37,40,47,[57][58][59] (and references therein). Irradiation with photon energies above the band gap, by contrast, produces delocalized, quasi-free conduction band electrons by ionization of water.…”

Section: Introductionmentioning

confidence: 99%

Below Band Gap Formation of Solvated Electrons in Neutral Water Clusters?

et al. 2020

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Below band gap formation of solvated electrons in neutral water clusters using pump–probe photoelectron imaging is compared with recent data for liquid water and with above band gap excitation studies in liquid and clusters. Similar relaxation times on the order of 200 fs and 1–2 ps are retrieved for below and above band gap excitation, in both clusters and liquid. The independence of the relaxation times from the generation process indicates that these times are dominated by the solvent response, which is significantly slower than the various solvated electron formation processes. The analysis of the temporal evolution of the vertical electron binding energy and the electron binding energy at half-maximum suggests a dependence of the solvation time on the binding energy.

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Transient spectra, formation, and geminate recombination of solvated electrons in pure water UV-photolysis: an alternative view

Cited by 55 publications

References 48 publications

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

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

Is there any Correlation between the Mobility and the Absorption Spectra of Solvated Electrons in Polar Solvents?

Below Band Gap Formation of Solvated Electrons in Neutral Water Clusters?

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