Electron Emission into Dielectric Liquids

The current between polished nickel electrodes immersed in pure toluene has been measured as a function of electric field (over the range 0 to 250,000 volts/cm) and of temperature (from - 15 to 70°C). The Richardson lines are straight but show a very small slope (0.05 to 0.4 ev) and a small value of the constant $A$ (${10}^{-9\mathrm{}}$ to ${10}^{-11\mathrm{}}$ amp./${\mathrm{cm}}^2$ ${\mathrm{deg}.\mathrm{}}^2$). The $logi \mathrm{vs}.\mathrm{} E^{\frac{1}{2}}$ curves show a slope about twice the value $\frac{e^{\frac{3}{2}}}{D^{\frac{1}{2}}\mathrm{kT}}$ predicted by the simple Schottky theory, but in agreement with the theory of Baker and Boltz. It is found however that there are serious objections to this theory, and the agreement with it is probably accidental. The situation is in fact too complex to be handled by a simple theory. It is suggested that for the low potential barrier present at the metal-dielectric interface a combination of thermionic and field currents would be expected which would account qualitatively for the observed behavior.