Über die Ladungsträgererzeugung in organischen Flüssigkeiten

At higher temperatures organic liquids show an intrinsic conductivity with an activation energy E1which is characteristic for each substance. With carbonyl compounds a linear relation between E1and the wave number v of the infrared vibration of the C=O group is observed. Therefore a linear decrease of E1with increasing portion of the polar valence-band structure C+⃝—C-⃝within the carbonyl-bond can be assumed. Within one molecule this polar structure forms a “short-living ion-pair” which can be excited thermally out of the resonance state by the energy E′. If ECoulis the COULOMB energy necessary to separate the electron from the “ion-pair”, the total energy required to form a charge-carrier is: E1= E′ + ½ ECoul. Charge-transfer-complexes, always present as impurities, enable a similar formation of charge-carriers. In this case it holds E′=0 and one obtains the activation energy for the low temperature conductance of organic liquids: E2=e2/2 ε r. The model explains the activation energy without involving relatively high optical molecular levels.