Electron scavenging in the radiolysis of supercritical butenes

Electron scavenging reactions with N2O have been studied in γ-irradiated supercritical butenes in the density range 0.25-0.48 g/cm3 at 170 +- 1 deg C. Free ion yields were estimated as a function of density from the nitrogen yields by means of the 'square root' model. The estimated G(free ion) in butenes increased with the decrease in density, and were in the order cis-2-butene >= isobutene > trans-2-butene at a given density. The density-normalized range of electrons estimated from G(free ion) values was independent of density over the density range studied. The magnitude of the reactivity parameter A in trans-2-butene was much larger than that in other butenes studied, but it generally increased with a decrease in density. An analysis of the parameter on the basis of the Nernst-Einstein relationship indicates that the trend is related to the change in the encounter efficiency of the reaction e- + N2O. (author)