Determination of surface heterogeneity profiles on graphite by finite concentration inverse gas chromatography.

Inverse gas chromatography (IGC) is an established tool in the determination of the adsorption potential distribution function. This function reflects the energetic heterogeneity profile of a surface and therefore provides interesting information on the nature and population of different surface sites. IGC is shown to be a fast and accurate technique for the determination of the adsorption potential distribution function of two different graphite samples. In this paper the adsorption of acidic and basic organic vapours is studied. Unlike heterogeneity profiles determined by nitrogen measurements, experiments with polar vapours can provide additional information on the adsorption mechanism and polar sorption sites. The heterogeneity profiles of all probes used are significantly different from one another and allow discreet energy levels to be distinguished. Chemically different probes reveal different adsorption mechanisms for the graphite surface.