Adsorption thermodynamics of monomers with non additive interactions

PINTO O. A; RAMÍREZ-PASTOR A.J.; NIETO F. D.

Mar del Plata

Congreso; Pan-American Advanced Studies Institutes (PASI-2006) ?From Disordered systems to Complex Systems; 2006

We present a Monte Carlo study of the adsorption process forparticles which interact by means of non additive coupling. Inparticular, we consider the case when the interaction energylinearly increases with the number of occupied nearest neighborsites. Such rules mimic the expected kind of interactions in knownexperimental problems with surface reconstruction. We describe andanalyze the behavior of thermodynamic quantities, such as theadsorption isotherms, isosteric heat, thermodynamic factor, etc., asa function of both temperature and coverage. Wecompare, discuss and explain the main differences with the morestudied case where the interactions are additive. We also presentthe critical behavior of the system by means of a finite-sizescaling method. The phase diagram is discussed in terms of thedifferent ordered phases present in the problem. The influence ofthe phase diagram in the behavior of thermodynamic and kineticquantities is discussed. Finally, the computational results are compared with Bragg-Williams and quasi-chemical approximations.