Stable electronic charge carriers have been observed in n-hexane, n-pentane, benzene, and methylbutene with room temperature mobilities of 0.07, 0.07, 0.6, and 3.6 cm2 V−1·sec−1, respectively. The charge carriers were injected into the highly purified hydrocarbon liquids by photoemission of electrons from a low work function surface. Mobilities increase rapidly with temperature and obey an Arhennius expression with activation energies of 4.3 kcal mole−1 in hexane and 2.6 kcal mole−1 in methylbutene. The carriers in hexane could be drawn out of the liquid into the vapor and had a higher mobility in the solid than in the liquid at temperatures near the melting point. Current versus voltage measurements indicate that the injection process is controlled by transmission over the image barrier at the cathode. The mobilities of the injected charges in these fluids are more than 100 times ionic mobilities in the same fluids but considerably less than the mobilities of electrons in the rare-gas liquids. The free electron theory of Cohen and Lekner, somewhat successful in explaining electron mobilities in the rare-gas liquids, does not give a satisfactory explanation of the hydrocarbon mobilities. A proposed generalization of the Cohen–Lekner theory to account for the effect of internal configurations of the hydrocarbon molecules on electron scattering also seems unable to explain the magnitudes and temperature dependence of the observed mobilities. A trapping model, in which the electron is frequently trapped for short times and otherwise moves as a free electron, appears to explain the mobility properties observed.

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The Cohen-Lekner kinetic theory of electron transport in simple systems is extended to polyatomic systems. The single-scatterer approximation is used to construct differential scattering cross sections for electron-molecule scattering in which the dependence on certain internal parameters such as molecular orientations and conformations, which vary with periods short compared to the duration of an electron-molecule collision, is accounted for by a fixedinternal-coordinates approximation.The resulting differential cross section, unlike the case treated by Cohen and Lekner, does not factor into a product of the electron-single-scatterer cross section and the Van Hove spectral function. The most important consequence of the internal parameters of the scattering molecules is the appearance of an incoherent scattering effect. Such an effect can be very important in liquids and solids where, because of intermolecular order, the coherent part of the cross section may be very small. Boltzmann's equation for electrons moving in a constant electric field is derived, solved formally for arbitrary field strength, and solved explicitly for a low-field limit.

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