Theory of Radiation Chemistry. II. Track Effects in Radiolysis of Water

Samuel, Aryeh H.; Magee, John L.

doi:10.1063/1.1699113

Cited by 299 publications

(67 citation statements)

References 16 publications

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“…Radicals escaping these regions would diffuse and react with a solute or become distributed more uniformly [14]. Magee [29] and Samuel and Magee [30] expressed a diffusion theory, taking into account this non-homogeneous behavior of ionizing radiation. They used the term of -spur‖ to characterize a cluster of reactive species.…”

Section: Water Radiolysis: a Brief Historical Surveymentioning

confidence: 99%

Water Radiolysis: Influence of Oxide Surfaces on H2 Production under Ionizing Radiation

Caër

2011

Water

507

309

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Abstract:The radiolysis of water due to ionizing radiation results in the production of electrons, H  atoms,  OH radicals, H 3 O + ions and molecules (dihydrogen H 2 and hydrogen peroxide H 2 O 2 ). A brief history of the development of the understanding of water radiolysis is presented, with a focus on the H 2 production. This H 2 production is strongly modified at oxide surfaces. Different parameters accounting for this behavior are presented.

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Section: Water Radiolysis: a Brief Historical Surveymentioning

confidence: 99%

Water Radiolysis: Influence of Oxide Surfaces on H2 Production under Ionizing Radiation

Caër

2011

Water

507

309

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“…T h e classical discussion of the motion of an electron in a condensed phase in the vicinity of a positive ion was given by Samuel and Magee (10). Following Onsager (11) they defined a critical escape distance r, for the electron where its thermal energy (KT) was equal to its coulombic potential energy.…”

Section: The Diffusion and Trapping Of Electrons I N M T H F Glasses mentioning

confidence: 99%

Photochemistry of Electrons Trapped in Glasses of Methyltetrahydrofuran at 77°k

Dyne¹,

Miller²

1965

Can. J. Chem.

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I n the radiolysis of methyltetrahydrofuran glass a t 77 "I< electrons are produced with a high yield. These are immobilized in traps in the glass and do not recombine with positive ions. They can be released from their traps by illumination with visible and infrared light and may then diffuse to positive ions and be captured. The quantum efficiencies for bleaching have been measured as a function of wavelength. This quantum efficiency falls as bleaching proceeds and depends on the fraction of the electrons bleached and not on their concentrations. About half the electrons are trapped close to positive ions and, on release, have a high probability of diffusing to the positive ion. The remaining half are trapped hon~ogeneously. On release from their traps, few of these electrons reach positive ions although they diffuse over long distances before being retrapped in the glass. This behavior is compared to that discussed by Samuel and Magee for the thermalization and capture of electrons in liquid water.The rate of recombination of an electron and positive ion in a condensed phase is an alinost unltnown quantity and the uncertainties which remain about this process lie a t the root of inany fundainental problems of radiation chemistry. Important advances, permitting a direct study of the process under special conditions, have, however, recently been inade by W. H. Hamill who has extended to radiolytic reactions the techniques of studying the photocheinistry of organic glasses which were pioneered by G. N. In an organic glass a t low teinperature reactive interinediates forined in radiolytic or photolytic decoinposition are held iininobile in a rigid solvent cage. They have long lifetimes and can be observed, a t leisure, by conventional optical techniques. Ronayne, Guarino, and Hamill (2) (henceforth R. G. and H.) found that, on radiolysis of glasses of 2-methyltetrahydrofuran (i\lITHF), a strong optical absorption is observed in the near infrared kvhich is due to electrons trapped in the glass. In glasses containing biphenyl as a solute the intensity of the electron band is reduced and a new absorption due to the biphenyl anion 4~ appears.'The electron band is photosensitive, being bleached by visible and near infrared light. If biphenyl is present in a bleaching experinlent the intensity of the biphenyl anion band increases as the intensity of the electron band is diminished. Electrons released froin their traps in the the glass inay be captured by positive ions or by biphenyl molecules.In a sense this technique allows one to observe, in slow motion, the recombination of electrons and positive ions. This paper describes a study of the photocheinistry of the bleaching of trapped electrons in i\lITHF glasses which shows that thermal electrons have a high mobility in the glass. While few electrons recoinbine with the positive ion before being trapped, they prefer trapping locations in the vicinity of positive ions. E X P E R I M E N T A LThe experimental techniques for purifying M T H F , making optical cell...

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“…Table I contains values some the track quantities which depend on the velocity only. 6 The last column of if the LET is small enough, the core is made up of a string of spurs rather than a continuous distribution of intermediates. The penumbra is made up of tracks of knock-on electrons, and it is always more inhomogeneous than the core.…”

Section: Tobiasmentioning

confidence: 99%