ABSTRACT
The interest of the biochemist in the diffusion of protons or, more precisely, the propagation of acidity near a membrane emerges directly from the basic theory of Bioenergetics. This chapter discusses how the experimental methods provide information pertinent to a comprehensive understanding of the subject. The virtual impermeability of the surface causes an asymmetry of the diffusion space and in parallel may provide a substrate for a two-dimensional diffusion. The macroscopic measurements of proton propagation at a phospholipid water interface exploit the relative ease of making monolayers at the water-air interface. Measurements of protonic diffusion at interfaces poses a severe technical difficulty as to how to suppress all information emerging from bulk water while collecting the data representing the surface. Swelling of dried phospholipids by added water is a complex process, leading to formation of multilamellar vesicles.
