Surface potential of monomolecular films

The vibrating plate capacitor, often referred to as the Kelvin probe, is used widely for measuring the surface charge on insulating surfaces and for measuring the contact potential of solids. The technique can also provide important information on the properties of monomolecular films both at the air/water interface and as layers deposited onto solid substrates. Mono- and multilayer films of molecular solids are receiving considerable attention at present because of their potential applications as molecular sensors and in molecular electronics. In many cases, the films of interest are formed initially as ordered molecular arrays at the air/water interface and then deposited, one molecular layer at a time, to form a Langmuir-Blodgett (LB) film. The authors show that the surface potential measurements provide a useful method of rapidly and easily investigating some fundamental properties of these molecular films