Positronium Formation in Solid Long-Chain Alkanes

• Authors: R. Zaleski , J. Wawryszczuk , T. Goworek
• Languages of publication: 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

EN

36.10.Dr; 78.70.Bj

Discipline

• 78.70.Bj: Positron annihilation(for positron states, see 71.60.+z in electronic structure of bulk materials; for positronium chemistry, see 82.30.Gg in physical chemistry and chemical physics)
• 36.10.Dr: Positronium(see also 82.30.Gg Positronium chemistry)

• Publisher: Institute of Physics, Polish Academy of Sciences
• Journal: Acta Physica Polonica A
• Year: 2005
• Volume: 107
• Issue: 4
• Pages: 635-641

Dates

published

2005-04

received

2004-09-20

Contributors

author

R. Zaleski

• Institute of Physics, Maria Curie Skłodowska University, pl. Marii Curie-Skłodowskiej 1, 20-031 Lublin, Poland

author

J. Wawryszczuk

• Institute of Physics, Maria Curie Skłodowska University, pl. Marii Curie-Skłodowskiej 1, 20-031 Lublin, Poland

author

T. Goworek

• Institute of Physics, Maria Curie Skłodowska University, pl. Marii Curie-Skłodowskiej 1, 20-031 Lublin, Poland

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Identifiers

DOI

10.12693/APhysPolA.107.635