Femtosecond attachment of excess electron to the water pool of Aerosol OT reversed micelles

Gauduel, Y.; Pommeret, S.; Yamada, N.; Migus, A.; Antonetti, A.

doi:10.1021/ja00195a062

Cited by 41 publications

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“…There are many reports on photoionization behavior of phenothiazine in different organic and micellar solutions [19][20][21][22][23][24][25], but little attention has been paid on the reaction between excited phenothiazine and electron-deficient compounds via photoinduced electron transfer. Recently, He et al had investigated the electron transfer reaction between PTH and maleic anhydride as well as the related chemically induced dynamic electron polarization effect by TR-ESR [18].…”

Section: Introductionmentioning

confidence: 99%

Proton transfer in phenothiazine photochemical oxidation: Laser flash photolysis and fluorescence studies

et al. 2007

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Section: Introductionmentioning

confidence: 99%

Proton transfer in phenothiazine photochemical oxidation: Laser flash photolysis and fluorescence studies

et al. 2007

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“…[48][49][50] Flash photolysis of halide ions in aqueous solutions provides the opportunity for investigation of electron transfer steps via direct electron photodetachment or charge transfer to solvent states (CTTS states) and for discussion of the results in the framework of quantum MD simulations of transient electronic configurations of ionic solute. [51][52][53][54][55][56][57] Recent UV, visible, and IR femtosecond photophysical investigations on electron detachment dynamics via one-(4 eV) or two-photon (2 × 4 eV) excitation of aqueous chloride ions have permitted the identification of multiple electronic states within the first 2 ps following energy deposition, in particular, high-and low-excited CTTS states, infrared prehydrated electron (excited hydrated electron), and hydrated electron ground states (eq 1). 56,57 Additional near-infrared spectroscopic investigations of twophoton excitation of aqueous ionic solute (Cl -) have permitted us to clearly identify electron-chlorine atom pairs.…”

Section: Introductionmentioning

confidence: 99%

Short-Time Electron Transfer Processes in Ionic Aqueous Solution: Counterion and H/D Isotope Effects on Electron−Atom Pairs Relaxation

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Gauduel

1996

J. Phys. Chem.

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Counterion and H/D isotope substitution effects on early electron transfer steps in aqueous sodium chloride solution (X 2 O/NaCl ) 55, X ) H,D) have been investigated by femtosecond absorption spectroscopy of short-lived electron-chlorine atom pairs in the 18500-8000 cm -1 spectral range. The frequency dependence of the overall signal rise time and early signal decay (geminate recombination process) from 1.77 to 2.29 eV has been analyzed in the framework of inhomogeneous populations of hydrated electron for which the absorption bands overlap in the visible spectral region. By use of a kinetic model, two well-defined electron hydration channels have been discriminated. The spectral signature of a delayed hydration channel (ehyd ′) is fully developed 4.5 ps after the initial energy deposition in the sample against 1.4 ps for the fastest electron hydration channel (ehyd ). Compared to the absorption band of the hydrated electron ground state (ehyd ), which peaks around 1.7 eV, the eHyd ′ population exhibits a spectral blue shift of about 0.15 eV. This electronic ground state is assigned to a polaron-like state, i.e., an electron localized in the vicinity of sodium ion: {e -‚‚‚Na + } hyd . The time-resolved spectroscopic experiments demonstrate that this electron localization process can be triggered by short-range counterion effects on transient electron-chlorine atom pairs ({Cl:e -} pair :Na + ). The existence of selective H/D isotope substitution effects on short-lived electronic configurations of aqueous Cl -(electronCl atom) pairs provides direct evidence that solvent cage dynamics around Cl -can differently interfere with multiple electron transfer channels. Contrary to infrared presolvated electron relaxation (p-like excited hydrated electron), early electron-chlorine atom pair relaxation (Cl:e -f Cl -) or 1D geminate recombination of fully hydrated electron with chlorine atom (Cl + ehyd f Cl -) for which no significant isotope effect is observed, the electron transfer process involving the deactivation of {Cl:e -} pair :(Na + ) population is drastically influenced by a change of intramolecular OH/OD vibrational mode frequency. In aqueous NaCl solution, the electron photodetachment from these transient electronic configurations [{Cl:e -} pair :(Na + )] f {Cl}, {e -‚‚‚Na + } hyd ] takes place with a characteristic time of 750 fs in H 2 O and 980 fs in D 2 O. The complete buildup of a polaronlike state (second electron hydration channel) is delayed by a factor of 1.6 (4.5 ps in H 2 O and 7.4 ps in D 2 O) when the energetic vibrational modes of water molecules (OH vs OD) are decreased by 2. The conjugate effects of very fast responses and slower cooperative motions of water molecules during short-range (electronatom) pairs -Na + couplings and a second electron hydration channel are discussed.

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“…First, in many ultrafast studies, the TA spectra were too sparsely sampled: the TA kinetics were obtained for just 4-to-10 wavelengths of the probe light. e.g., [3][4][5]13,17 This sparse sampling makes it impossible to verify the central tenet of the "continuous shift" model, viz. the constancy of the spectral profile during the thermalization process.…”

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Solvation and Thermalization of Electrons Generated by above-the-Gap (12.4 eV) Two-Photon Ionization of Liquid H₂O and D₂O

2005

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Temporal evolution of transient absorption (TA) spectra of electrons generated by above-the-gap (12.4 eV total energy) two-photon ionization of liquid H2O and D2O has been studied on femto- and picosecond time scales. The spectra were obtained at intervals of 50 nm between 0.5 and 1.7 mum. Two distinct regimes of the spectral evolution were observed: t < 1 ps and t > 1 ps. In both of these regimes, the spectral profile changes considerably with the delay time of the probe pulse. The "continuous blue shift" and the "temperature jump" models, in which the spectral profile does not change as it progressively shifts, as a whole, to the blue, are not supported by our data. Furthermore, no p-state electron, postulated by several authors to be a short-lived intermediate of the photoionization process, was observed by the end of the 300 fs, 200 nm pump pulse. For t < 1 ps, two new TA features (the 1.15 microm peak and 1.4 mum shoulder) were observed for the electron in the spectral region where O-H overtones appear in the spectra of light water. These two features were not observed for the electron in D2O. The 1.4 mum peak observed in D2O may be the isotope-shift analogue of the 1.15 microm feature in H2O. Vibronic coupling to the modes of water molecules lining the solvation cavity is a possible origin of these features. On the sub-picosecond time scale, the absorption band of solvated electron progressively shifts to the blue. At later delay times (t > 1 ps), the position of the band maximum is "locked", but the spectral profile continues to change by narrowing on the red side and broadening on the blue side; the oscillator strength is constant within 10%. The time constant of this narrowing is ca. 0.56 ps for H2O and 0.64 ps for D2O. Vibrational relaxation and time-dependent decrease in the size and sphericity of the solvation cavity are suggested as possible causes for the observed spectral transformations in both of these regimes.

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Femtosecond attachment of excess electron to the water pool of Aerosol OT reversed micelles

Cited by 41 publications

References 0 publications

Proton transfer in phenothiazine photochemical oxidation: Laser flash photolysis and fluorescence studies

Proton transfer in phenothiazine photochemical oxidation: Laser flash photolysis and fluorescence studies

Short-Time Electron Transfer Processes in Ionic Aqueous Solution: Counterion and H/D Isotope Effects on Electron−Atom Pairs Relaxation

Solvation and Thermalization of Electrons Generated by above-the-Gap (12.4 eV) Two-Photon Ionization of Liquid H₂O and D₂O

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Femtosecond attachment of excess electron to the water pool of Aerosol OT reversed micelles

Cited by 41 publications

References 0 publications

Proton transfer in phenothiazine photochemical oxidation: Laser flash photolysis and fluorescence studies

Proton transfer in phenothiazine photochemical oxidation: Laser flash photolysis and fluorescence studies

Short-Time Electron Transfer Processes in Ionic Aqueous Solution: Counterion and H/D Isotope Effects on Electron−Atom Pairs Relaxation

Solvation and Thermalization of Electrons Generated by above-the-Gap (12.4 eV) Two-Photon Ionization of Liquid H2O and D2O

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Solvation and Thermalization of Electrons Generated by above-the-Gap (12.4 eV) Two-Photon Ionization of Liquid H₂O and D₂O