Observation of a persistent infrared absorption following two photon ionization of liquid water

Birkedal, Victoria; Madsen, Esben Svitzer Yates; Petersen, Christian; Johnsen, Mette; Seegert, Asbjørn; Jensen, Svend Knak; Keiding, Søren Rud; Thøgersen, Jan

doi:10.1016/j.chemphys.2006.06.017

Cited by 9 publications

(11 citation statements)

References 30 publications

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“…The matching irradiance dependencies of THz and NIR responses shown in Supplementary Figure 2 prove that the THz signal indeed originates from excess electrons for all pump-wavelengths. The 266 nm and 400 nm pump data follow the expected second-and thirdorder power laws [24,35], whereas the 800 nm pump signal depicts a threshold behavior with ≈1 TW/cm 2 as the onset of ionization. Such a threshold behavior indicates that a strong-field ionization rather than a multiphoton mechanism is behind the photo detachment with 800 nm photons, in accordance with the conclusions from Ref.…”

Section: Resultsmentioning

confidence: 99%

“…That is, it leaves our THz observation window after ≈200 fs (Fig. 1), then appears in the mid-IR [9-11, 23, 24] and eventually the NIR spectral range upon full solvation [10,14,24]. Afterwards, the hydrated electron recombines in a diffusive process on a much slower timescale (Fig.…”

Section: Discussionmentioning

confidence: 99%

“…According to a simple particle-in-a-box picture, such a localization should be accompanied by a shift in the absorption spectrum from potentially the THz or even GHz regions over the mid-IR to the VIS spectral range. The latter stages of this process have indeed been observed by femtosecond pump-probe experiments in the mid-IR [9-11, 23, 24] or NIR/VIS regime [10,14,24], but the initial frequency at which this process starts, which is directly related to the initial degree of delocalization of the excess electron, has not yet been explored.…”

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confidence: 97%

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Direct observation of the collapse of the delocalized excess electron in water

et al. 2014

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It is generally assumed that the hydrated electron occupies a quasi-spherical cavity surrounded by only a few water molecules in its equilibrated state. However, in the very moment of its generation, before water has had time to respond to the extra charge, it is expected to be significantly larger in size. According to a particle-in-a-box picture, the frequency of its absorption spectrum is a sensitive measure of the initial size of the electronic wavefunction. Here, using transient terahertz spectroscopy, we show that the excess electron initially absorbs in the far-infrared at a frequency for which accompanying ab initio molecular dynamics simulations estimate an initial delocalization length of 40 Å. The electron subsequently shrinks due to solvation and thereby leaves the terahertz observation window very quickly, within 200 fs.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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confidence: 97%

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Direct observation of the collapse of the delocalized excess electron in water

et al. 2014

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“…The only explicitly geometry‐related property derived from the spectroscopic data is the spin density gyration radius . Directly observed structure‐related properties are optical spectra in UV‐ and IR‐regions, EPR g‐factors and the binding energy . The lack of direct experimental measurements of the structure of the hydrated electron calls for theory, although reliable modelling of

e_{a q}^{-}

is at least equally challenging as the corresponding experiments.…”

Section: Figurementioning

confidence: 99%

Dynamics of the Bulk Hydrated Electron from Many‐Body Wave‐Function Theory

2019

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The structure of the hydrated electron is a matter of debate as it evades direct experimental observation owing to the short life time and low concentrations of the species. Herein, the first molecular dynamics simulation of the bulk hydrated electron based on correlated wave‐function theory provides conclusive evidence in favor of a persistent tetrahedral cavity made up by four water molecules, and against the existence of stable non‐cavity structures. Such a cavity is formed within less than a picosecond after the addition of an excess electron to neat liquid water, with less regular cavities appearing as intermediates. The cavities are bound together by weak H−H bonds, the number of which correlates well with the number of coordinated water molecules, each type of cavity leaving a distinct spectroscopic signature. Simulations predict regions of negative spin density and a gyration radius that are both in agreement with experimental data.

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“…[1] Theo nly explicitly geometry-related property derived from the spectroscopic data is the spin density gyration radius. [2] Directly observed structure-related properties are optical spectra in UV- [1b, 3] and IR-regions, [4] EPR g-factors [5] and the binding energy. [6] Thel ack of direct experimental measure-ments of the structure of the hydrated electron calls for theory,a lthough reliable modelling of e À aq is at least equally challenging as the corresponding experiments.…”

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confidence: 99%

Dynamics of the Bulk Hydrated Electron from Many‐Body Wave‐Function Theory

2019

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The structure of the hydrated electron is amatter of debate as it evades direct experimental observation owingtothe short life time and lowc oncentrations of the species.H erein, the first molecular dynamics simulation of the bulk hydrated electron based on correlated wave-function theory provides conclusive evidence in favor of ap ersistent tetrahedral cavity made up by four water molecules,and against the existence of stable non-cavity structures.Such acavity is formed within less than ap icosecond after the addition of an excess electron to neat liquid water,w ith less regular cavities appearing as intermediates.T he cavities are bound together by weak HÀH bonds,the number of whichcorrelates well with the number of coordinated water molecules,e acht ype of cavity leaving ad istinct spectroscopic signature.S imulations predict regions of negative spin density and ag yration radius that are both in agreement with experimental data.

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Observation of a persistent infrared absorption following two photon ionization of liquid water

Cited by 9 publications

References 30 publications

Direct observation of the collapse of the delocalized excess electron in water

Direct observation of the collapse of the delocalized excess electron in water

Dynamics of the Bulk Hydrated Electron from Many‐Body Wave‐Function Theory

Dynamics of the Bulk Hydrated Electron from Many‐Body Wave‐Function Theory

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