High electric field conduction in aromatic hydrocarbons: effects of the polymerization

The electrical conduction of purified toluene in the negative tip-plane electrode geometry was studied for high electric field. Mean current-voltage characteristics and current pulses (apparent charge, frequency) were measured for different tip radii. Above a threshold electric field of 4.2±0.6 MV/cm, the results depended greatly on the previous use of the tip. For the first measurements made with a given tip, the I-V curve showed a current jump at voltage V_s. For voltages greater than this threshold voltage, regular pulses were detected. The threshold voltage and the characteristics of the pulses were studied. After a long use of the tip, the pulse regime faded out. Erratic pulses were detected only for voltages much greater than V_s . The current jump was no longer observed at V_s. Mean I-V characteristics and current pulses were influenced by an organic deposit at the used tip. This deposit is due to the polymerization of toluene liquid