Femtochemistry of the Hydrated Electron at Decimolar Concentration

Pommeret, S.; Gobert, F.; Mostafavi, Mehran; Lampre, Isabelle; Mialocq, J.C.

doi:10.1021/jp0123381

Cited by 74 publications

(78 citation statements)

References 34 publications

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“…The femtosecond UV excitation can result in the generation of hydrated electrons (see, e.g., refs. [24,25]). To suppress absorption signals due to hydrated electrons, sodium nitrate was added to the sample solutions.…”

Section: Methodsmentioning

confidence: 99%

The Excited‐State Decay of 1‐Methyl‐2(1H)‐pyrimidinone is an Activated Process

et al. 2011

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The photophysics of 1-methyl-2(1H)-pyrimidinone (1MP) dissolved in water is investigated by steady-state and time-resolved fluorescence, UV/Vis absorption, and IR spectroscopy. In the experiments, excitation light is tuned to the lowest-energy absorption band of 1MP peaking at 302 nm. At room temperature (291 K) its fluorescence lifetime amounts to 450 ps. With increasing temperature this lifetime decreases and equals 160 ps at 338 K. Internal conversion (IC) repopulating the ground state and intersystem crossing (ISC) to a triplet state are the dominant decay channels of the excited singlet state. At room temperature both channels contribute equally to the decay, that is, the quantum yields of IC and ISC are both approximately 0.5. The temperature dependence of UV/Vis transient absorption signals shows that the activation energy of the IC process (2140 cm(-1)) is higher than that of the ISC process (640 cm(-1)).

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Section: Methodsmentioning

confidence: 99%

The Excited‐State Decay of 1‐Methyl‐2(1H)‐pyrimidinone is an Activated Process

et al. 2011

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“…This effect is mainly the consequence of inhomogeneous absorption of light. 9, 17 In Fig. 2(b) (solid lines), the decay kinetics for homogeneous recombination of electrons averaged along the path of the probe light are simulated for the initial concentration profiles shown in Fig.…”

Section: Geminate Kinetics and The Escape Probabilitymentioning

confidence: 99%

Light-Induced Temperature Jump Causes Power-Dependent Ultrafast Kinetics of Electrons Generated in Multiphoton Ionization of Liquid Water

et al. 2004

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Picosecond geminate recombination kinetics for electrons generated by multiphoton ionization of liquid water become power dependent when the radiance of the excitation light is greater than 0.3-0.5 TW/cm 2 (the terawatt regime). To elucidate the mechanism of this power dependence, tri-400 nm photon ionization of water has been studied using pump-probe laser spectroscopy on the pico-and femtosecond time scales.We suggest that the observed kinetic transformations are caused by a rapid temperature jump in the sample. Such a jump is inherent to multiphoton ionization in the terawatt regime, when the absorption of the pump light along the optical path becomes very nonuniform. The heating of water is substantial (tens of o C) because the 3-photon quantum yield of the ionization is relatively low, ca. 0.42, and a large fraction of the excitation energy is released into the solvent bulk as heat. Evidence of the temperature jump is the observation of a red shift in the absorption spectrum of (thermalized) electron 2 and by characteristic "flattening" of the thermalization dynamics in the near IR. The temperature jump in the terawatt regime might be ubiquitous in multiphoton ionization in molecular liquids. The implications of these observations for femtosecond pulse radiolysis of water are discussed.

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“…Absolute 2PA cross sections have been reported at a limited number of discrete energies. [42][43][44][45][46] Most notably, Nikogosyan et al 42 observed a monotonic rise of the cross section for degenerate two-photon excitation with a picosecond laser at five energies ranging from 7.8 to 9.3 eV. The increasing 2PA across that range strongly contrasts with the distinct absorption band at 8.3 eV in the 1PA spectrum.…”

Section: Introductionmentioning

confidence: 99%

Electronic structure of liquid water from polarization-dependent two-photon absorption spectroscopy

Elles¹,

Rivera²,

Zhang³

et al. 2009

The Journal of Chemical Physics

106

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Two-photon absorption ͑2PA͒ spectroscopy in the range from 7 to 10 eV provides new insight on the electronic structure of liquid water. Continuous 2PA spectra are obtained via the pump-probe technique, using broadband probe pulses to record the absorption at many wavelengths simultaneously. A preresonance enhancement of the absolute 2PA cross section is observed when the pump-photon energy increases from 4.6 to 6.2 eV. The absorption cross section also depends on the relative polarization of the pump and probe photons. The variation of the polarization ratio across the spectrum reveals a detailed picture of the 2PA and indicates that at least four different transitions play a role below 10 eV. Theoretical polarization ratios for the isolated molecule illustrate the value of the experimental polarization measurement in deciphering the 2PA spectrum and provide the framework for a simple simulation of the liquid spectrum. A more comprehensive model goes beyond the isolated molecule picture and connects the 2PA spectrum with previous one-photon absorption, photoelectron, and x-ray absorption spectroscopy measurements of liquid water. Previously unresolved, overlapping transitions are assigned for the first time. Finally, the electronic character of the vertical excited states is related to the energy-dependent ionization mechanism of liquid water.

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Femtochemistry of the Hydrated Electron at Decimolar Concentration

Cited by 74 publications

References 34 publications

The Excited‐State Decay of 1‐Methyl‐2(1H)‐pyrimidinone is an Activated Process

The Excited‐State Decay of 1‐Methyl‐2(1H)‐pyrimidinone is an Activated Process

Light-Induced Temperature Jump Causes Power-Dependent Ultrafast Kinetics of Electrons Generated in Multiphoton Ionization of Liquid Water

Electronic structure of liquid water from polarization-dependent two-photon absorption spectroscopy

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