Electron scavenging in ethanol and in water

Ražem, Dušan; Hamill, William H.

doi:10.1021/j100532a005

Cited by 39 publications

(19 citation statements)

References 9 publications

(12 reference statements)

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“…(W) Experimental data; (v, 0) theoretical rate constant( k , , k2).conductance of each type of ion in the solution. By use of the limiting equivalent conductance of e-sol (1 70 cm2 $2-' equiv-')(Matheson, 1965) and of Na+ (45 cm2 E' equiv-') (Robinson 8zStokes, 1959), the relaxation time of the ionic atmosphere of e-sol is found to be 290 ps. This time is longer than the experimental half-lifetime of the reaction e-sol + NAD' (tl12 = log 2T = 215 ps for NAD', 0.101 M, pH 6.7).…”

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confidence: 99%

Femtosecond charge separation in organized assemblies: free-radical reactions with pyridine nucleotides in micelles

Gauduel¹,

Berrod²,

Yamada³

et al. 1988

Biochemistry

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Femtosecond laser UV pulse-induced charge separation and electron transfer across a polar interface have been investigated in anionic aqueous micells (sodium lauryl sulfate) containing an aromatic hydrocarbon (phenothiazine). The early events of the photoejection of the electron from the micellized chromophore and subsequent reaction of electron with the aqueous perimicellar phase have been studied by ultrafast infrared and visible absorption spectroscopy. The charge separation (chromophore +...e-) inside the micelle occurs in less than 10(-13) s (100 fs). The subsequent thermalization and localization of the photoelectron in the aqueous phase are reached in 250 fs. This results in the appearance of an infrared band assigned to a nonrelaxed solvated electron (presolvated state). This transient species relaxes toward the fully solvated state of the electron in 270 fs. In anionic aqueous micelles containing pyridine dinucleotides at high concentration (0.025-0.103 M), a single electron transfer can be initiated by femtosecond photoionization of phenothiazine. The one-electron reduction of the oxidized pyridine dinucleotide leads to the formation of a free pyridinyl radical. The bimolecular rate constant of this electron transfer depends on both the pH of the micellar system and the concentration of oxidized acceptor. The free-radical reaction is analyzed in terms of the time dependence of a diffusion-controlled process. In the first 2 ps following the femtosecond photoionization of PTH inside the micelle, an early formation of a free pyridinyl radical is observed. This suggests that an ultrafast free-radical reaction with an oxidized form of pyridine nucleotide can be triggered by a single electron transfer in less than 5 X 10(11) s-1.

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confidence: 99%

Femtosecond charge separation in organized assemblies: free-radical reactions with pyridine nucleotides in micelles

Gauduel¹,

Berrod²,

Yamada³

et al. 1988

Biochemistry

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“…Selected irradiations were performed in an open glass tube in order to study the effect of oxygen on the radiation degradation. Buxton et al (1988) 9.0 × 10 6 Koehler et al (1985) 9.1 × 10 8 Buxton et al (1988) 7.9 × 10 9 Ashton et al (1995) 7.2 × 10 6 Gordon et al (1977) 1.1 × 10 9 Roduner and Bartels (1992) 7.7 × 10 9 Nickelsen et al (1994) 1.3 × 10 7 Marketos et al (1974) 1.3 × 10 7 Bansal et al (1971) Chlorobenzene 5.6 × 10 9 Ashton et al (1995) 9.1 × 10 8 Ye (1989) 1.4 × 10 9 Lichtscheidl and Getoff (1979b) 4.3 × 10 9 Nickelsen et al (1994) 5.0 × 10 8 Lichtscheidl and Getoff (1979a) 1,2-Dichlorobenzene Neta and Schuler (1975) 4.4 × 10 7 Afanassiev et al (1979) 3.6 × 10 6 Draganic et al (1973) 3.0 × 10 7 Razem and Hamill (1977) 1.4 × 10 6 Neta et al (1971a) 3.8 × 10 7 Verma and Fessenden (1976) 2…”

Section: Apparatusmentioning

confidence: 99%

Radiation-Induced Degradation and the Effect of Scavengers on Benzene, Monochlorobenzene and 1,2-Dichlorobenzene in Aqueous Solutions

Takriti

2004

Water Quality Research Journal

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The degradation of benzene, monochlorobenzene and 1,2-dichlorobenzene in aqueous solution by gamma irradiation was investigated. The effect of the irradiated solution composition was studied. The results showed that benzene is more resistant to destruction than chlorinated benzenes. The presence of oxidizing and reducing reactive species and the rapid reaction rates with halogenated benzenes increased the degradation rate of the pollutants. Dechlorination of CB and 1,2-DCB was observed. High performance liquid chromatography (HPLC) and spectroscopy (UV-Vis) were used to monitor changes in the radiation solutions. The final aqueous irradiation products were shown to be a complex mixture of by-products. The addition of scavengers such as methanol and ethanol required larger doses to decompose the pollutants when compared to those solutions with no additives.

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“…In polar solutions, intermolecular electron transfer faster than the picosecond solvation process has been investigated by fluorescence up-conversion − but up to now competitive nonreactive electron dynamics (electron solvation) and ultrafast presolvation radical reactions in water have not be investigated at very short times. Nanosecond and picosecond pulse radiolysis studies have suggested that ultrafast radical reaction (univalent reduction of a solute) would involve hot electrons or short-lived precursors of hydrated electron. − These indirect investigations determine the subnanosecond G value of solvated electrons for different electron scavenger concentrations. The pulse radiolysis experiments treat the data by determining empirical relationships between the rate constant of an electron transfer and the C 37 value, − or stochastic analysis of competitive electron solvation and electron capture .…”

Section: Introductionmentioning

confidence: 99%

“…Nanosecond and picosecond pulse radiolysis studies have suggested that ultrafast radical reaction (univalent reduction of a solute) would involve hot electrons or short-lived precursors of hydrated electron. − These indirect investigations determine the subnanosecond G value of solvated electrons for different electron scavenger concentrations. The pulse radiolysis experiments treat the data by determining empirical relationships between the rate constant of an electron transfer and the C 37 value, − or stochastic analysis of competitive electron solvation and electron capture . The investigations of ultrafast electron transfers at the macroscopic level do not permit one (i) to understand in detail presolvation intermolecular charge transfer, and (ii) to determine the exact nature of early branching between short-lived nonreactive and reactive electronic configurations.…”

Section: Introductionmentioning

confidence: 99%

Ultrafast Reactivity of IR-Excited Electron in Aqueous Ionic Solutions

1998

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An ultrafast presolvation reaction involving IR-excited hydrated electrons and bivalent metal cations (Cd2+)aq was investigated at the femtosecond time scale. The initial electron photodetachment is triggered by a two-photon UV excitation of aqueous chloride ions (R = [H2O]/[XCl2] = 110). The photodetached electron reaches a IR p-like state (prehydrated electron) with a time constant of 130 fs at 294 K. In the presence of nonreactive divalent alkaline metal cations (X2+ = Mg2+), this transient IR electronic state exhibits a deactivation process toward the ground state of hydrated electron (s state) with a time constant of 300 ± 20 fs. In aqueous CdCl2 solution, an ultrafast IR electron transfer channel (univalent reduction of Cd2+ by IR prehydrated electrons) competes with the p → s transition of trapped electrons (electron solvation process). This presolvation reaction occurs with a characteristic time of 140 ± 20 fs. Within the electron solvation regime, this elementary redox process is totally achieved in less than 1 × 10-12 s and exhibits a probability 10 times higher than the electron hydration channel. The consequence of an early partition between reactive and nonreactive IR electron dynamics on the subpicosecond formation of fully hydrated electron is discussed. The femtosecond IR spectroscopy of excited p-state electron transfer processes in aqueous electrolyte solutions opens a new area of prethermal reactions in environments relevant to mainstream chemistry and biochemistry.

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Electron scavenging in ethanol and in water

Cited by 39 publications

References 9 publications

Femtosecond charge separation in organized assemblies: free-radical reactions with pyridine nucleotides in micelles

Femtosecond charge separation in organized assemblies: free-radical reactions with pyridine nucleotides in micelles

Radiation-Induced Degradation and the Effect of Scavengers on Benzene, Monochlorobenzene and 1,2-Dichlorobenzene in Aqueous Solutions

Ultrafast Reactivity of IR-Excited Electron in Aqueous Ionic Solutions

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