Positronium formation and quenching in frozen and liquid solutions in octanol

Abstract

Pure octanol is examined in the liquid and solid state, together with solutions of two solutes promoting both inhibition and quenching of positronium (Ps): quinone, a Ps oxidizer, and free radical TMOPO, promoting Ps spin conversion reactions. In all cases, the changes of both the Ps lifetime and, to a lesser extent, intensity denote the five phase transitions expected between 123 and 294 K. In contrast to a previous claim, no Ps quenching reactions are observed in the frozen solutions while Ps inhibition through electron capture by the solutes in the positron spur appears to be sensitive to the phase. In the liquid phase, the quenching reaction rate constants of either solute are higher by a factor of ∼4 than what is expected on the basis of conventional expressions for diffusion-controlled reactions.