Electron trapping by methanol aggregates in dilute solution in nonpolar solvents

Gangwer, T.; Allen, Augustine O.; Holroyd, Richard A.

doi:10.1021/j100530a007

Cited by 18 publications

(54 citation statements)

References 5 publications

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“…Thus, in agreement with Gangwer et al 25 we conclude, contrary to Baxendale and co-workers, 20-24 that only higher multimers trap the electron in alcohol solutions at equilibrium. To make more quantitative estimates, the following model was used: 25 The alcohol molecules were assumed to cluster according to reactions (4) with the equilibrium constants K n given in section 2.2, and solvated electrons e solv − were assumed to attach to these multimers via reaction (3) with the equilibrium constants K eq n ( ) . The tacit assumption of this scheme is that reactions (3)…”

Section: Alcohols In N-hexanesupporting

confidence: 93%

“…For methanol at 23 o C, the tetramer also provides the best fit to the data (not shown). The latter result is in agreement with Gangwer et al 25 who suggested tetramer or pentamer as the predominant electron trapping ROH n ( ) cluster for solutions of methanol in iso-octane and tetramethylsilane. Van't Hoff plots for the equilibrium constants of reaction (3) obtained using these two models are shown in Fig.…”

Section: Alcohols In N-hexanesupporting

confidence: 92%

“…This behavior (for 1-propanol) is in agreement with the pulse radiolysis -TA study by Baxendale and Rasburn. 23 Gangwer et al 25 reported that the bimolecular rate constant k k c eff ≈ ∆ for electron scavenging by methanol in iso-octane decreases from 4x10 8 M -1 s -1 (the same limiting rate constant was obtained by Baxendale and Rasburn) 23 increasing ratio r at longer delay times t L ). In principle, the initial increase in the decay rate k may be explained by a scavenging reaction involving electron-attaching impurity present in the solute, such as an aldehyde.…”

Section: Alcohols In N-hexanesupporting

confidence: 54%

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Electron Trapping by Polar Molecules in Alkane Liquids: Cluster Chemistry in Dilute Solution

Shkrob

Sauer

2005

J. Phys. Chem. A

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Experimental observations are presented on condensed-phase analogues of gas-phase dipole-bound anions and negatively charged clusters of polar molecules. Both monomers and small clusters of such molecules can reversibly trap conduction band electrons in dilute alkane solutions. The dynamics and energetics of this trapping have been studied using pulse radiolysis-transient absorption spectroscopy and time-resolved photoconductivity. Binding energies, thermal detrapping rates, and absorption spectra of excess electrons attached to monomer and multimer solute traps are obtained, and possible structures for these species are discussed. "Dipole coagulation" (stepwise growth of the solute cluster around the cavity electron) predicted by Mozumder in 1972 is observed. The acetonitrile monomer is shown to solvate the electron by its methyl group, just as the alkane solvent does. The electron is dipole-bound to the CN group; the latter points away from the cavity. The resulting negatively charged species has a binding energy of 0.4 eV and absorbs in the infrared. Molecules of straight-chain aliphatic alcohols solvate the excess electron by their OH groups; at equilibrium, the predominant electron trap is a trimer or a tetramer, and the binding energy of this solute trap is ca. 0.8 eV. Trapping by smaller clusters is opposed by the entropy that drives the equilibrium toward the electron in a solvent trap. For alcohol monomers, the trapping does not occur; a slow proton-transfer reaction occurs instead. For the acetonitrile monomer, the trapping is favored energetically, but the thermal detachment is rapid (ca. 1 ns). Our study suggests that a composite cluster anion consisting of a few polar molecules imbedded in an alkane "matrix" might be the closest gas-phase analogue to the core of solvated electron in a neat polar liquid.

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Section: Alcohols In N-hexanesupporting

confidence: 93%

Section: Alcohols In N-hexanesupporting

confidence: 92%

Section: Alcohols In N-hexanesupporting

confidence: 54%

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Electron Trapping by Polar Molecules in Alkane Liquids: Cluster Chemistry in Dilute Solution

Shkrob

Sauer

2005

J. Phys. Chem. A

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“…alcohol-hydrocarbon mixtures have been investi-1 gated in the liquid (1)(2)(3)(4)(5)(6) and glassy states (7)(8)(9)(10)(11)(12)(13)(14).…”

mentioning

confidence: 99%

Electron trapping in alcohol clusters in γ-irradiated n-propanol–hydrocarbon glasses at 77 K

Ito¹,

Kimura²,

Fueki³

1981

Can. J. Chem.

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MASAYA ITO, TOYOAKI KIMURA, and KENJI FUEKI. Can. J. Chem. 59, 2803 (1981). A study has been made of trapped electrons in n-propanol-hydrocarbon mixture glasses at 77 K by the optical absorption method. 1The yields of electrons trapped in alcohol clusters (e&) were measured for several y-irradiated n-propanol-hydrocarbon glasses, where the yields of trapped electrons in these neat hydrocarbon glasses at 77 K are known to range from 0.015 to 1.1 G units. The results show that the yields of e, . -in the mixture glasses do not depend on the trapped electron yields in neat hydrocarbon glasses. Thus, it is concluded that electron migration from relaxed hydrocarbon matrix traps into alcohol clusters is not the major process for eal,-formation in the systems studied here. The major process for eal,-formation may be attributed to quasi-free electron scavenging by alcohol clusters and electron migration from unrelaxed hydrocarbon traps into alcohol clusters. Both ir-induced and isothermal changes in the ea,-yield have also been investigated. These investigations indicate that there is a correlation between the observed change in the eal,-yield and the matrix viscosity.

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“…After the basic studies of Baxendale, Keene, and Rasburn,11 mixtures of this kind were studied by Gangwer et al 12 and by Beck and Thomas. 8 Electron mobility in pure hydrocarbons j.Lo is regarded 3 to be a weighted mean of the mobility in the quasifree state j.LF and of that in the localized state j.LL' viz., j.Lo =Pj.LL + (1-P)j.LF' For n-hexane, P= O.…”

Section: Percolation In Homogeneous Mixturesmentioning

confidence: 99%

Percolation model of electron and hole mobility in liquid mixtures

Schiller

Nyikos

1980

The Journal of Chemical Physics

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The theory of charge percolation, originally developed for inhomogeneous mixtures of metals, is transformed to describe mobility of electrons and holes in homogeneous liquid mixtures. Systems in which the energies of the charge carriers are independent of composition are expected to obey the predictions of this formalism. Here concentration fluctuations act as microscopic inhomogeneities. As examples, hole mobility in trans -decaline-cyclohexane, and electron mobility in hexafluorobenzene-benzene and in n-hexane-ethanol mixtures are treated. The number of molecules interacting with a charge carrier appears as an important parameter. Mobility versus concentration curves are calculated in the entire concentration range and are in good agreement with observations. Finally a method is proposed for estimating electron mobility in hexafluorobenzene.

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Electron trapping by methanol aggregates in dilute solution in nonpolar solvents

Cited by 18 publications

References 5 publications

Electron Trapping by Polar Molecules in Alkane Liquids: Cluster Chemistry in Dilute Solution

Electron Trapping by Polar Molecules in Alkane Liquids: Cluster Chemistry in Dilute Solution

Electron trapping in alcohol clusters in γ-irradiated n-propanol–hydrocarbon glasses at 77 K

Percolation model of electron and hole mobility in liquid mixtures

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