Dissolved oxygen and positronium atom in liquid media

Abstract

The interaction of positronium (Ps) with molecular oxygen dissolved in liquids (isooctane, cyclohexane, isopropanol and water) is experimentally investigated. For variation of the O 2 concentration the liquids were bubbled with Ar, air and O 2. For interpretation of the lifetime annihilation spectra a simple deconvolution of the spectra into three exponentials decaying in time was used. These exponents correspond to para-positronium, free positron and ortho-positronium annihilations. The total reaction rate constant of the Ps atom with dissolved oxygen (which is the sum of two-ortho-para-conversion (Ps → ¼ p-Ps + ¾ o-Ps) and oxidation (Ps + O 2 → e + + O 2-) reaction rate constants) is obtained for each liquid.