화학공학소재연구정보센터
Journal of Physical Chemistry A, Vol.105, No.6, 991-994, 2001
Temperature, pressure and solvent dependence of positronium reactivity toward nitrobenzene
Positronium (Ps) reaction rates, with weak acceptors(Ac) (such as nitrobenzene) leading to the formation of Ps-Ac complexes, have long been known to exhibit intriguing features: nonmonotonic temperature dependence (at variance with the usual Arrhenius behavior), considerable variation in characteristics with different solvents, and anomalies with respect to external pressure at ambient temperature (large changes in some media and hardly any in others). We present precise measurements performed in our laboratory on the temperature dependence of the reaction rate (kappa) for Ps toward nitrobenzene in benzene as the solvent, determining in particular, the "turnover point" (or rather the region) carefully, a result which when taken in juxtaposition with earlier experimental findings by Kobayashi, vis-a-vis external pressure dependence of the rate in benzene versus other solvents, enables us to provide a natural semiquantitative explanation in the context of the bubble model of Ps in liquids.