Papers by Author: Jan Wawryszczuk

Abstract: The distribution of electron trap depths in hydrocarbons seems to be continuous in the range from 0.6 eV to 2.2 eV. However, it seems that among the deepest traps in n-heptane also the discrete ones appear as well. The influence of the admixture of other alkane on Ps intensity in alkanes was examined. As far as the admixture of an alkane with a shorter chain is concerned, the depth of the traps and their amount remain almost the same like in the case of the pure solvent. When it comes to essentially non-miscible solid heptane and nonane, a total lack of electron accumulation effects was observed. It is an exception among the mixed alkanes investigated here and needs a careful study.

Abstract: A review of data about positron annihilation lifetime in normal alkanes is presented. It was found that positronium in rigid phase locates in the interlamellar gap, while in the rotator one in free volumes inside lamellae. Interesting effects seem to be: identity of o-Ps lifetime in rotator and liquid phase in long chain alkanes; appearance of “premature” rotator phase in nonadecane with low tricosane admixture, long-term relaxation after the changes of temperature or pressure in some binary mixtures, formation of porous structure at solidification of argon saturated alkane under high pressure.

Abstract: Positron lifetime spectra were measured for several alkanes under high pressure of argon and nitrogen. In the case of argon intercalation, the dependence of melting temperature on pressure is nonmonotonous, while in nitrogen this effect does not appear.