Changes in Contact Potentials of Metalss Caused by Adsorbed Monolayers

摘要

A classic problem inn the physics and chemistry of surfaces has been the successful utilization of changes in the contact potential difference between two metals as a means of studying surface properties and adsorption. Recent advances in experimental techniques, especially the use of a flurorcarbon coating on the reference elec trode, have made possible a number of advances in the study of the surface potential changes resulting from the adsorption of mono-layers of nonpolar liquids and of the higher molecular weight polar compounds. Studies have been made of adsorbed non-polar liquid compounds including the various hydrocarbons and carbon tetrachloride. Polar-nonpolar compounds, such as the homologous families of the fatty acids and amines as well as certain aromatic phosphate esters, have alslalso been investigated with the new techniques. Reproducible and interesting results have been obtained, even though the measurements were made in the presence of atmospheric oxygen, nitrogen, and water vapors as well as any surface oxide development on the metal at ordinary temperatures; however, it was necessary to control the relative humidity and air temperature carefully, to use an atmosphere entirely free of organic vapors or polar inorganic compounds, to take great care in cleaning the metal surfaces, and to employ compounds of extremely high purity. (Author)