Electron mobilities in liquid olefins: Structure effects

Abstract

Electron mobilities (square centimeters per volt second) at 293°K and their activation energies (kilocalories per mole) in several liquid olefins are, respectively, cis-butene-2, 2.2 and 3.7; trans-butene-2, 0.029 and 5.4; 2, 3-dimethylbutene-2, 5.8 and 2.0; cyclohexene, 1.0 and 3.6. Mobilities in butene-1 and isobutene at 293°K are 0.064 and 1.44 cm2/v· sec, respectively. The mobilities in all of the liquids are independent of electric field strength in the range 1–14 kV/cm. Molecular dipole moments up to 0.5 D have negligible effects on the magnitudes of the mobilities. A plot of the thermal electron mobilities against epithermal electron ranges in the olefins falls on the same curve as that for electrons in saturated hydrocarbons. This implies that molecular negative ion states are not involved in the scattering processes that control the thermal electron mobilities, nor in those that limit the epithermal electron ranges. Attempts to measure electron mobilities in conjugated dienes failed, presumably due to capture of the thermalized electrons by the dienes to form molecular negative ions.