The Effect of Visible Light Irradiation on Positronium Formation in Polyethylene at Low Temperature

Abstract

The effect of visible light exposing on the ortho-positronium formation in polyethylene was studied. Lifetime spectra of positrons in polyethylene were measured in the temperature range between 50 K and 370 K. It was observed that the visible light quenches the enhancement of ortho-positronium intensity (I3) at lower temperature than ca. 250 K -the glass transition temperature of polyethylene. On the other hand, the lifetime of ortho-positronium component (T3) was not affected by the presence of the visible light.

Influence of Positron Irradiation on Positronium Formation in n-Alkanes

“…The electrons located in such traps may be removed by illumination of the sample by the light with a sufficient quantum energy. The influence of light on Ps formation in polymers at low temperatures has been studied by Hirade et al [5][6][7]. Other processes which influence the Ps formation are pointed out in Refs.…”

Positronium as a probe of small free volumes in crystals, polymers and porous media

“…After illumination the o-Ps intensity returns to the initial low value, like for non-irradiated sample. The experiments of this kind were performed by Hirade et al [183,184], Ito et al [185] with polymer samples, and followed by other authors applying the light to throw electrons out the traps in alkanes [186,187]. Fig.…”

A Comparison of Different Theoretical Models of Positron Lifetime Spectra for Polymers

“…Just above T g it bends a bit and next it continues the increase. The bend is often observed at I 3 at low temperatures and reflexes decrease in Ps formation above T g , because of release of radiation-induced electrons [21][22][23] from shallow electron traps in polymer structure.…”