Trapped Electrons and Radicals in γ-Irradiated Propylene Carbonate Glasses

Shaede, Eric A.

doi:10.1139/v72-122

Cited by 8 publications

(16 citation statements)

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“…The structure of this radical is also pertinent to studies recently initiated by Kevan and co-workers (14) concerning the environment of the trapped electron in MTHF glasses at various temperatures. Both 2-MTHF and propylene carbonate (15) are structurally similar, form stable glasses at 77 K, and would be expected to yield tertiary radicals, as was seen previously for aliphatic alkane systems (16). The exact mechanism of radical formation in the pure phase glassy state is still speculative, but could involve H+-transfer from neighbouring parent ions.…”

Section: Of Particular Interest To Radiation Chemistssupporting

confidence: 56%

Structure of radicals produced by γ-radiolysis. Part 4. Adamantane matrices doped with various 5-membered heterocyclic molecules

Winters¹,

Ling²

1976

Can. J. Chem.

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D. L. A. CAMPBELL LING. Can. J. Chem. 54, 1971 (1976). The effects of y-radiolysis at room temperature on adamantane and adamantane-dl, matrices doped with 5-membered heterocyclic molecules has been examined by X-band electron spin resonance (esr) spectrometry. Radical structures formed from heterocyclic solute molecules are discussed and tentative assignments made for 2-methyl-, 3-methyl-, and 2,5-dimethylthiophene, 2-methyl-, and 2,5-dimethylfuran. Discussion of possible radical structures derived from furan, tetrahydrofuran, 2-methyl-and 3-methyltetrahydrofuran, 2,5-dihydrofuran, and 4,5-dihydro-2-methylfuran, is included, but unambiguous assignments of structure cannot be made for these compounds from the esr data obtained. Other molecules examined included thiophene, pyrrole, and I-methyl-and 1,2,5-trimethylpyrrole. For these latter molecules, experimentally obtained first derivative X-band esr spectra were too poorly resolved to allow rational discussion of possible structures. It was noted that perdeuterated adamantane matrices provided superior resolution for esr spectra derived from radicals with a delocalized spin center such as ally1 or allenyl species. D. L. WINTERS et A. CAMPBELL LING. Can. J. Chem. 54, 1971Chem. 54, (1976. On a examine par la spectrometrie rpe de la bande X les effets de la radiolyse y, a la temperature de la piece, sur des matrices d'adamantane et d'adamantane-dl, dopees avec des molecules heterocycliques a cinq membres. On discute des structures radicalaires formees a partir des molecules de solutes hetCrocycliques et on fait des attributions non-definitives pour le methyl-2, le methyl-3 et le dimethyl-2,5 thiophtne et le methyl-2 et le dimethyl-2,5 furanne. On inclut aussi une discussion des structures radicalaires possibles pouvant derivees du furanne, du tetrahydrofuranne, des methyl-2 et -3 tetrahydrofuranne, du dihydro-2,5 furanne et du dihydro-4,5 methyl-2 furanne; toutefois on ne peut faire d'attributions non-ambiques pour ces composes a partir des donnees rpe obtenues. Parmi les autres molecules qui ont ete examinees, on note le thiophene, le pyrrole et les methyl-1 et trimethyl-1,2,5 pyrroles. Pour ces dernitres molecules, les premitres derives obtenues expCrimentalement a partir des spectres rpe de la bande X ne sont pas assez bien resolus pour permettre une discussion rationnelle des structures possibles. On a note que les matrices de perdeutiroadamantane fournissent une meilleure resolution pour les spectres rpe derives des radicaux avec un centre de spin delocalise, tels que les esptces allyle et allenyle.[Traduit par le journal]

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Section: Of Particular Interest To Radiation Chemistssupporting

confidence: 56%

Structure of radicals produced by γ-radiolysis. Part 4. Adamantane matrices doped with various 5-membered heterocyclic molecules

Winters¹,

Ling²

1976

Can. J. Chem.

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“…Again, the central lines are often very broad in the spectra in ref. 1, although in several instances they are of nearly the correct intensity (cfi Fig. 2a).…”

Section: (B) the Proton Hyperfine Componentsmentioning

confidence: 88%

“…2b, 4a, and 4b of ref. 1. Because of the effect of various physical constraints upon certain of these components, it was suggested that they comprise three sets of doublets, designated B, D, and E, with proton coupling constants of 42, 83, and 124 G respectively (1).…”

Section: (B) the Proton Hyperfine Componentsmentioning

confidence: 99%

“…also offered, and a n attempt is made to explain This paper describes a continuation of a recent the effect of changes in temperature on ihese study (1) of radiation effects in glassy propylene hyperfine features. carbonate (4-methyl-2-dioxoloni; hereafter, PC), Experimental which reference be for an Details were as described previously (1) except that a duct or^ survey the subject.…”

Section: Introductionmentioning

confidence: 99%

“…carbonate (4-methyl-2-dioxoloni; hereafter, PC), Experimental which reference be for an Details were as described previously (1) except that a duct or^ survey the subject. In this (11, a central more powerful 60Co Source was used, giving a nominal narrow e.s.r.…”

Section: Introductionmentioning

confidence: 99%

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Further Studies of γ-Irradiated Propylene Carbonate Glasses

Shaede¹,

Symons²

1973

Can. J. Chem.

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An earlier postulate, that physically trapped electrons (e,-) are responsible for a narrow e.s.r. singlet at g = 2.0028 formed by exposure of glassy propylene carbonate to 60Co y-rays at 77 OK, is re-examined. An alternative, that propylene carbonate radical anions are formed, in which the extra electron is largely confined to an antibonding orbital on the carbonate moiety, is favored. The primary new evidence for this anion is the detection of satellite e.s.r. lines which were lost on bleaching or thermal decay of the central line, and which occurred in the correct: field regions to be assigned to I3C hyperfine structure from the carbonate carbon of the anion.The complicated set of proton hyperfine lines is now assigned largely to the radical 1 and the mechanisms by which this radical may be formed are discussed. The previously observed temperature dependence of the proton hyperfine features can now be understood in terms of thermal restrictions on the motions of the methyl group and the adjacent n~ethylene protons.On a CtudiC de nouveau un arcien postulat selon lequel des Clectrons pikgCs physiquement (et-) sont responsables de I'Ctroit singulet en R.S.E. i g = 2.0028 consCcutivement B I'exposition du carbonate de propylkne vitreux a des rayons-y '"To B 77 O K . On favorise une autre alternative selon laquelle il se formerait des anions radicalaires du carbon,ate de propylene oil I'Clectron en surplus serait surtout limit6 a une orbitale anti-liante de I'entitC carbonate. Le nouvel argument principal en faveur de cet anion est la detection de bandes satellites en r.s.e. lesquelles sont perdues lors de la decoloration ou de la dkgCnCrescence thermique de la bande centrale et qui apparaissent dans les bonnes regions du champ pour pouvoir itre attribukes a la structure hyperfine du I3C appartenant au carbone du carbonate de I'anion. Le patron compliquC des bandes hyperfines du proton est maintenant attribuC surtout au radical 1 et les mCcanismes responsables de la formation de ce radical sont discutes. La relation dCjB observCe entre les bandes hyperfines du proton et la tempCrature peut maintenant ttre expliquC en termes de restrictions thermiques sur les mouvements du groupe mCthyl et des protons du groupe mCthylene adjacent.[Traduit par le journal]Can.

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