Molecular Structure Effects on the Freehyphen;Ion Yields and Reaction Kinetics in the Radiolysis of the Methylhyphen;Substituted Propanes and Liquid Argon: Electron and Ion Mobilities

摘要

The freehyphen;ion yields in liquid alkanes increase with increasing molecular sphericity and increasing temperature, in agreement with earlier observations. The Arrhenius temperature coefficient of freehyphen;ion formation is 0.8 kcalsol;mole in propane and 0.7 kcalsol;mole in 2hyphen;methylpropane. The freehyphen;ion yield in purified argon at 87deg;K appears to beGfiequals;2.0. Addition of oxygen to liquid argon decreased the freehyphen;ion yield, mainly because the efficiencies of electron energy loss processes with the diatomic oxygen molecules were much greater than those with monatomic argon molecules; the oxygen served to decrease the ionmdash;electron separation distance more by dehyphen;energizing the electron than by scavenging it before it reached the end of its normal track. In pure liquid oxygen at 87deg;K,Gfiequals;0.013. The ionmdash;electron neutralization rate constant equals8 times; 10minus;5thinsp;cm3sol;ionmiddot;secin pure argon at 87deg;K and3.1 times; 10minus;4thinsp;cm3sol;ionmiddot;secin liquid methane at 120deg;K. The mobility of electrons in liquid methane is300thinsp;cm2sol;Vmiddot;secand decreases in other hydrocarbons with decreasing sphericity of the molecules. The Arrhenius temperature coefficient of electron mobility in 2hyphen;methylpropane is 3 kcalsol;mole. Ionmdash;ion neutralization rate constants in the present liquids were all of the order of 10minus;9cm3sol;ionmiddot;sec, and the ion mobilities were all in the vicinity of10minus;3thinsp;cm2sol;Vmiddot;sec.