C. Rybka

Temperature effects in positronium formation: Solid aromatic hydrocarbons

Abstract The temperature dependence of the probability of positronium formation was investigated in a series of solid aromatic hydrocarbons. The results are dis

Positronium in solid phases of phenanthrene

Abstract Temperature dependence of positronium formation in phenanthrene was investigated. On crossing the solid-solid phase transition point in both directions a sharp decrease of positronium creation probability was observed. The effect is discussed in terms of formation of an unstable phase, and of possible pyroelectricity of phenanthrene.

Positron annihilation and phase transitions in n-octadecanol

Abstract The positronium formation probability and the mean lifetime in n-octadecanol-1 were observed as a function of temperature. The changes of that probability are discussed in the terms of the spur reaction model, suggesting the residual effect of dielectric constant increase in the rotational phase.

Temperature dependence of three-quantum annihilation in organic crystals

Abstract The three-quantum annihilation intensity in molecular crystals was measured as a function of temperature. It was shown that the thermally induced long-lived component observed earlier in the time spectrum arises from ortho-Ps decay.

Electric field effects in positron annihilation in phenanthrene

Abstract The variations of positronium formation probability at changes of temperature of phenanthrene were investigated. All observed effects can be explained as the results of electric field inhibition of Ps formation in a pyroelectric medium.