On the influence of electron mobilities on the yields of formation of positronium in liquids: New I3 measurements and Monte Carlo simulations

Billard, Isabelle; Goulet, T.; Jay‐Gerin, Jean‐Paul; Bonnenfant, A.

doi:10.1063/1.475624

Cited by 10 publications

(5 citation statements)

References 41 publications

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“…Thus, efficient e ϩ scattering at the blob formation stage results in approximately spherical shape of the blob. Therefore, the simulation of the end part of the e ϩ track by the straight-line sequence of isolated ion-electron pairs 45 or by a cylindrical column of ionizations 48 seem to be unjustified.…”

Section: B Recombination Mechanism Of Ps Formation: Spur and Blob Momentioning

confidence: 99%

Electric field effect on positronium formation in liquids

Stepanov

Byakov

2002

The Journal of Chemical Physics

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The comparison of different models (the Ore, spur and blob models) of positronium (Ps) formation is presented. Because in molecular media Ps is formed in the terminal positron blob and not in an ordinary spur, the application of the blob model seems to be the most adequate. We extend this model for consideration of the Ps formation in the presence of external electric field ($<100$ kV/cm). In the simplified limiting case, this approach provides a formula similar to the Onsager one for the geminate recombination probability. The influence of ion-electron recombination and other intrablob processes on Ps formation is taken into account. The role of quasifree positronium in Ps formation process is discussed

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Section: B Recombination Mechanism Of Ps Formation: Spur and Blob Momentioning

confidence: 99%

Electric field effect on positronium formation in liquids

Stepanov

Byakov

2002

The Journal of Chemical Physics

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“…9 More recently, Kobayashi et al studied the effect of polar ethylene vinyl acetate copolymer ͑EVA͒ on Ps formation in nonpolar polyethylene. 10 It was found that at low concentrations the o-Ps intensity is decreased, but at high concentrations it is increased by the addition of EVA.…”

Section: Introductionmentioning

confidence: 99%

Electric-field dependence of positronium formation in liquids and polymers

et al. 1998

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Positron annihilation lifetime measurements have been performed to study the effect of an external electric field on the probability of positronium ͑Ps͒ formation in several liquids ͑isooctane, hexane, cyclohexane͒ and polymers ͓polystyrene, poly͑4-methyl-1-pentene͒, low-and high-density polyethylene, polypropylene, polycar-bonate͔. The ortho-positronium intensity I 3 for all the samples except polar polycarbonate decreased with increasing external electric-field strength in the range of 0-60 kV/cm. Based on the Onsager equation, the average initial spatial separation between a positron and an electron in the terminal positron spur has been deduced to be 10-44 nm for the nonpolar polymers, 21-52 nm for the degassed liquids, and 19-37 nm for the air-saturated liquids, indicating that the average thermalization distance of the positron is larger than that of an excess electron. It is shown that the time required for Ps formation is on the order of 10 ps.

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“…A wide compilation of I 3 data was gathered in a number of pure liquids to be compared with the known mobility m(e À ) of electrons in these media. 155 In the particular cases of tetramethylsilane, 2,2-dimethylbutane and n-hexane, where information on the temperature dependence of the density, the electron thermalization distance and m(e À ) is available, the correlation between ortho-Ps formation and m(e À ) has been calculated by Monte Carlo simulation techniques, and the respective roles played by the mean thermalization distances of e À and e , their thermal mobilities and the dielectric constant of the liquid were investigated. The rate constants of the ortho-into para-Ps conversion reactions were measured by means of positron annihilation lifetime spectroscopy for checking the electron delocalization in Cr II .…”

Section: Positronium and Muonium Chemistrymentioning

confidence: 99%

7 Radiation chemistry

Belloni

Delcourt

Houée-Levin⊥

et al. 2000

Annu. Rep. Prog. Chem., Sect. C

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We try in this review to survey advances in all the aspects of Radiation Chemistry (the effects of high energy or ionizing radiation), both basic and applied, made during the period 1995^1999, after the last report issued at the end of 1994. 1 Classically, two main classes of studies are relevant. The ¢rst one includes the primary phenomena induced by the interaction of high-energy radiation with a chemical system. The way the energy is spatially deposited is indeed highly nonhomogeneous and depends on the type of radiation considered. Mutual reactions between the primary species produced also depend on their initial spatial distribution, and therefore on the energy absorption pattern. The kinetic aspects derive directly from the initial events following radiation absorption and thus, when observed at times as short as possible, give useful information on the early energy distribution for each of the radiation types, X-and g-photons, electrons and heavy particles, and, on the in£uence of their intensity and energy per particle.The second class of studies utilizes the background knowledge of radiation chemistry to generate and then to observe the fate of chemical transient species known to be involved in very important chemical or biochemical processes. Numerous data, such as the nature of reaction products, the absolute rate constants, the sequence of elementary reactions constituting a mechanism, and the thermodynamic and spectroscopic properties of short-lived species have been attained. This kind of study of transients and reaction mechanisms, which can be approached only by pulse techniques (essentially pulse radiolysis or laser photolysis, each with its speci¢c advantages), constitutes the new ¢eld of fast to ultrafast chemistry. It concerns extended domains of physical, organic, inorganic, and bio-chemistry. Moreover, the understanding of mechanisms is quite helpful in suggesting new ways of synthesis or degradation induced by irradiation and is now extensively used in developing various speci¢c processes in applied chemistry. The number of studies on the chemical mechanisms and in applied radiation chemistry constitutes an increased fraction of the total publications in radiation chemistry, which we estimate to be around 4000 over the period considered (almost constant compared to the preceding 5-year

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On the influence of electron mobilities on the yields of formation of positronium in liquids: New I3 measurements and Monte Carlo simulations

Cited by 10 publications

References 41 publications

Electric field effect on positronium formation in liquids

Electric field effect on positronium formation in liquids

Electric-field dependence of positronium formation in liquids and polymers

7 Radiation chemistry

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