Molecular Structure Effects on the Free-Ion Yields and Reaction Kinetics in the Radiolysis of the Methyl-Substituted Propanes and Liquid Argon: Electron and Ion Mobilities

Abstract

The free-ion yields in liquid alkanes increase with increasing molecular sphericity and increasing temperature, in agreement with earlier observations. The Arrhenius temperature coefficient of free-ion formation is 0.8 kcal/mole in propane and 0.7 kcal/mole in 2-methylpropane. The free-ion yield in purified argon at 87°K appears to be Gfi=2.0. Addition of oxygen to liquid argon decreased the free-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 ion—electron separation distance more by de-energizing the electron than by scavenging it before it reached the end of its normal track. In pure liquid oxygen at 87°K, Gfi=0.013. The ion—electron neutralization rate constant equals 8 × 10−5 cm3/ion · sec in pure argon at 87°K and 3.1 × 10−4 cm3/ion · sec in liquid methane at 120°K. The mobility of electrons in liquid methane is 300 cm2/V · sec and decreases in other hydrocarbons with decreasing sphericity of the molecules. The Arrhenius temperature coefficient of electron mobility in 2-methylpropane is 3 kcal/mole. Ion—ion neutralization rate constants in the present liquids were all of the order of 10−9 cm3/ion·sec, and the ion mobilities were all in the vicinity of 10−3 cm2/V · sec.

Effect of Electric Field Strength on the Free Ion Yields in the X-Radiolysis of Liquids: Influence of Molecular Structure and Temperature

“…7 . The values of G; in the present work agree with the free ion yields measured by applying an electric field after the radiation pulse (22), within experimental error (Table 1 ).…”

“…A rgon-Oxygen Systems Ion yields reported elsewhere (22) for liquid argon, argon-oxygen solutions, and liquid oxygen have now been analyzed according to eq. 5.…”

Electron Mobilities and Ranges in Liquid C1–C3 Hydrocarbons and in Xenon: Effects of Temperature and Field Strength

“…The sum of the anion and cation mobilities (u, + u-) was determined using an equation analogous to [5].…”

“…Of varticular inelectron mobility in liquid hydrocarbons is inversely related t o the magnitude of the mobility, being near zero for high mobilities and near 4 kcal/mol for low mobilities (2)(3)(4). Electrons in methane (5,6), argon (7)(8)(9), krypton (7,8), and xenon (8,10) have very high mobilities, and since ~~n u s u a l temperature effects had been noted in argon (7,9) and krypton (7), it was of interest to measure the effect of temperature on electron mobilities in methane and xenon. Measurements were made in the other hydrocarbons to complete the series of C, to C, niolecules.…”

Radiolysis Free Ion Yields and Electron Ranges in Polar and Nonpolar Liquids: Fluoromethanes

“…The values of y,,, obtained for the fluorocarbons are listed in Table 2. Electron Medium ranges of secondary electrons in a number of liquids are listed in Table 3 (8,(12)(13)(14). The liquid density has been used successfully to normalize ranges in hydrocarbons (2, 5, 9, 12), but density is less suitable for the normalization of ranges in different kinds of compounds.…”