Developments in the theoretical modelling and experimental measurement of the surface potential of condensed monolayers

In recent years considerable progress has been made in developing a theory for the surface potential of monolayers both at the air-water interface and deposited onto solid supports. This period has also seen the advent of scanning probe technology which has enabled surface potential to be measured to a hitherto undreamed of spatial resolution. This paper traces the key stages in these developments and explores the challenges that remain. Initially, the various models proposed for relating molecular and bond dipole moments to the surface potential are evaluated and the reliability of the moments obtained by applying the models to experimental results investigated. The limitations of the traditional Kelvin probe method of measuring surface potential are then highlighted and how these are overcome in the new generation of scanning force microscopes. Finally, it is suggested that such instruments could readily form the basis of a 'READ' head for a molecular memory based on a self-assembled, macromolecular lattice. (C) 2000 Elsevier Science B.V. All rights reserved.