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2005 | 107 | 4 | 635-641
Article title

Positronium Formation in Solid Long-Chain Alkanes

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EN
Abstracts
EN
This paper represents a fragment of systematic studies on positron annihilation in solid saturated hydrocarbons (alkanes, paraffins) from C_{17}H_{36} to C_{30}H_{62}. The Tao-Eldrup model and its extensions allow to identify the places in the crystalline structure where positronium is trapped, and estimate respective trap sizes. In the rigid phase I positronium locates mainly in two-dimensional empty spaces between the lamellae of crystal structure. Additional free volumes exist in high temperature phases due to appearance of n-alkane conformers representing a non-planar molecule distortion. The rise of ortho-positronium intensity with the sample irradiation dose, which was seen earlier in polymers, is observed also in n-alkanes. One can find similarities between the ortho-positronium annihilation in crystalline alkanes and polymers, like exponential character of that rise, and the trap bleaching by illumination. It confirms the same origin of the intensity growth, i.e. the accumulation of trapped electrons. Two kinds of electron traps were found. The time constant of electron accumulation in the traps depends on the carbon chain length and varies with temperature in different way for even- and odd-numbered alkanes.
Keywords
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Contributors
author
  • Institute of Physics, Maria Curie Skłodowska University, pl. Marii Curie-Skłodowskiej 1, 20-031 Lublin, Poland
  • Institute of Physics, Maria Curie Skłodowska University, pl. Marii Curie-Skłodowskiej 1, 20-031 Lublin, Poland
author
  • Institute of Physics, Maria Curie Skłodowska University, pl. Marii Curie-Skłodowskiej 1, 20-031 Lublin, Poland
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Document Type
Publication order reference
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YADDA identifier
bwmeta1.element.bwnjournal-article-appv107n413kz
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