’’Phase transitions’’ between dense monolayers of atoms and simple molecules on the cleavage face of graphite, with particular emphasis on the transition of nitrogen from a fluid to a registered monolayer

Adsorption isotherms of N2 on graphite have been studied in great detail in a coverage range corresponding to the transition between the fluid and the registered monolayer. This transition is first order up to a temperature of about 82 K. An adsorption isotherm at 84.69 K shows that the methane monolayer also changes from fluid to registered monolayer through a first order transition. A few adsorption isotherms of Kr and Ar are shown at coverages where a transition of a ’’higher order’’ occurs.