Transport of Electrons in Nonpolar Fluids

Abstract

Electron transport in nonpolar fluids has been investigated for several decades. At first the emphasis was on liquified rare gases, and later on excess electrons were also studied in molecular liquids such as alkanes. Now mobility data are available for approximately 75 nonpolar liquids ( 1). Progress in this field was hampered initially by impurities like O2, CO2, and various electrophilic compounds in the liquids. The availability of adequate methods of purification has stimulated experimental studies. Some new compounds have been studied recently, and new experimental techniques are being applied. Innovative theoretical approaches are now being tried. These efforts will eventually provide a better understanding of the basic problems of electron scattering and localization in liquids. Excess electrons can be introduced in liquids either by ionization or by injection. Ionization may utilize single or multiphoton absorption or high energy radiation. Injection can be from a cathode immersed in the liquid (photoelectric effect) or by field emission. Most studies of electron trans­ port require a short excitation pulse. The electrons produced thereby can be monitored by a number of techniques (2). One is that of DC conduc­ tivity. Even though ions may be concomitantly formed, electrons move much faster than molecular ions, therefore the current at short times is due to the motion of the electrons. Another technique is that of microwave