Two-stage adsorption and desorption processes in some nitroaromatic semiconductor-vapour systems : implications in compensation effect in dark conduction process

Adsorption and desorption ofn-hexane, cyclohexane, CCl4, C6H6 ethylacetate, methanol and ethanol vapours on the crystallite surfaces of 2-nitrofluorene and three isomeric nitrobenzoic acid semiconductors have been investigated using electrical conductivity as a probe. Kinetic analysis data show that in all these vapour-semiconductor systems, the adsorption is a two-stage process. Existence of any relationship between the adsorption process and the compensation effect in dark conduction process has been examined. The compensation effect is generally observed in cases where the change in semiconduction activation energy is caused by a two-stage adsorption process.