AROMATICITY, ELECTRONIC-STRUCTURE AND MOLECULAR DIMENSION IN THE ADSORPTION OF ORGANIC-COMPOUNDS ON MERCURY .2. INTERMOLECULAR INTERACTIONSAMONG ADSORBED MOLECULES

The Frumkin interaction parameter between aromatic molecules (neutral form) adsorbed from aqueous solution on mercury electrode, is related to the balance of energy dispersion terms (adsorbate-adsorbate) and wa ter-water molecular interaction reflecting the role played by substitu tion on the electrode surface of water by the aromatic molecule. The i nteraction among adsorbed aromatics (in neutral form) is always attrac tive, so that the sign of a(F) (Frumkin parameter, positive or negativ e) arises from that kind of balance. For aromatic anions, taking into account a large partial charge transfer from the adsorbate to the meta l surface, the change of Delta G(ADS)(0) at varying the coverage (thet a) is mainly due to electrostatic repulsion among charge adsorbed part icles. (C) 1997 Elsevier Science Ltd.