SCREENED INTERACTIONS IN CONDENSED MEDIA AND STATISTICAL TREATMENT OFPH-DEPENDENT MONOLAYER PHASE-BEHAVIOR OF LONG-CHAIN ALIPHATIC AMINO-ACIDS

An experimental and theoretical study has been made of intermolecular interactions in monolayers of 2-aminotetradecanoic acid molecules at a n air-water interface. A comparison of the interaction parameters requ ired to fit to experiment a statistical mechanical model derived herei n indicates strong screening between similarly charged ions. in the in terfacial region. An 'electrostricted' dielectric medium is an inappro priate description of the screening mechanism between ions of like cha rge. The free energy is minimised by the maintenance of a high degree of local screening by solvent molecules and other ions in the system.