Rates and energy of reactions of charged species in supercritical xenon

Richard A. Holroyd, Masaru Nishikawa and Kengo Itoh

Radiat. Phys. Chem., 74, 146-151 (2005). [Find paper at Elsevier Science Direct]

Abstract:

Pulse radiolysis was used to study the rates of several electron transfer reactions in supercritical Xe over a range of pressures. The rates of electron attachment to oxygen and 4,4'-bipyridine were also studied; the latter reaction is sufficiently fast to compete with electron­ion recombination, which is very fast in supercritical Xe. Electron transfer from 4,4'-bipyridine anion to benzoquinone is diffusion controlled. A peak in the rate is observed in the pressure region of maximum compressibility as expected for diffusion control. The rates of electron transfer from 4,4'-bipyridine anion and from hexafluorobenzene anion to O₂ are an order of magnitude slower than expected for diffusion. The energetics of these reactions is discussed.