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

Abstract

Electronmobilitiesweremeas~ired inethane, ethylene, propane,cyclopropane,and propylene tocomplete the sttidies of the lower hydrocarbons. The effect of temperature on the mobilities in these l i q~~i d s and in methane, 11-butane, and xenon were also measured. Exan~ples of the data are given in the order mobility (cm2/Vs), temperature (K), A r r h e n i~~s temperature coefficient (kcal/mol): methane, 430, 140, -0.16; ethane, 0.97,200, -3; ethylene, 0.0030, 170, -; propane, 0.55,238, -3 ; 17-butane,0.073,250, -4; cyclopropane, 0,0043,234, -4; propylene, 0,008,234, -4; xenon, -1200 at 4 0 V/cm, 198,O. The mobilities in the C2-C, hydrocarbons are independent of applied electric field strength E up to 20 kV/cm; that in methane is independent of E LIP to 2 kV/cm; that in xenon decreases as E-'I2 between 33 a n d 300 V/cm and decreasesslightly morerapidly at higherfieldstrengths. IntroductionThe Arrhenius temperature coefficient E,, for The penetration ranges of low energy (-10 eV) electrons into the simplest liquid hydrocarbons, C, to C, , have recently been estimated (I). The density-normalized range bd was related to the degree of sphericity and isotropy of polarizability of the molecules. It has since been shown that there is also a correlation between the mobility of thermal electrons and the penetration range of low energy electrons in a given liquid (2); electron ranges are large in liquids in which the mobilities are high, and vice versa. As the electron mobilities in the C, and C, hydrocarbons have not yet been reported, it was of interest to make these measurements and test the correlation. Of varticular in-

Molecular structure effects on electron ranges and mobilities in liquid hydrocarbons: chain branching and olefin conjugation: mobility model

“…Alketzes rltzcl Alkynes In liquid ethylene the range is snlaller than that in an alkane (9), which indicates that electron energy loss is Illore efficient in the former than in the latter. Substitution of the ethylenic hydrogens by methyl groups increases the electron range in the liquid olefin, but also gives rise to unexplained structure effects such as that in cis-and trans-2-butene ( Table 3).…”

“…However, the properties that govern these processes are not clearly known. In small alkanes the range increases with increasing degree of sphericity of the molecule (7,9), but the basic reason for it renlains t o be discovered. The properties that govern penetration in unsaturated hydrocarbons are obscure (5).…”

Electronic transport in disordered n-alkanes: From fluid methane to amorphous polyethylene

“…The behavior of excess electrons in n-alkane fluids has been extensively investigated [15][16][17][18][19] and represents a paradigm for the study of the transport properties of excess electrons in dielectric media. There are numerous measurements of the low-field electron mobility and the conduction band energy V 0 , defined as the difference of the photoelectric work function of a metal electrode when in contact with the material and in vacuum.…”

Effect of polymer polarity on the positronium formation

“…This indicates that the influence of the electric field on the decrease in I 3 is closed correlative with the polarity of the polymer. In previous studies on the electric field dependence of positronium formation, researchers mainly concentrated on various liquids11, 12 and homopolymers,13–15 and a some research has been undertaken on copolymers.…”