Phase transitions at electrochemical interfaces:: Evaluation of critical exponents for condensation of organic adsorbates

The surface pressure exerted by a monolayer of organic compounds condensing at electrochemical interfaces is evaluated using a two-dimensional nearest-neighbor Ising model formalism. The experimental critical temperature data of organic adsorbates are employed to obtain the composite short-range interaction energy using Onsagerʹs exact solution. The methodology of obtaining the critical exponents `δʹ and `γʹ pertaining to surface pressure and isothermal compressibility is discussed. These values are consistent with the exponents postulated in other contexts, thereby demonstrating the universality hypothesis.