Adsorption Thermodynamics of Interacting Particles on Self-Similar Substrates: Statistical Fractals

M. S. NAZZARRO; F. NIETO; A. J. RAMIREZ-PASTOR

PHYSICA A - STATISTICAL AND THEORETICAL PHYSICS

Elsevier

Lugar: Amsterdam; Año: 2004 vol. 331 p. 517 - 530

0378-4371

Grand canonical Monte Carlo simulations have been performed inorder to study adsorption thermodynamics of pairwise interactingparticles on fractal surfaces. Diffusion-limited aggregates(DLA)have been used as a substrate where interacting particles areadsorbed.In order to obtain aggregates with differentmorphologies,DLA clusters are generated on different stronglycorrelated surfaces.Adsorption isotherm,adsorption energy anddifferential heat of adsorption were calculated for attractive andrepulsive nearest-neighbor (NN)lateral interactions.For the caseof repulsive couplings and low temperatures,four novel orderedphases has been found in the adsorbate,each one corresponding tothe formation of a chessboard-like structure on sites withone,two,three and four NN sites,respectively.The values ofcoverage at which these ordered phases emerge are not symmetricalaround $\theta=0.5$ .This is a consequence of the non-equivalencebetween vacancy and particle in the case of adsorption on fractalstructures.The influence of ordered structures on thermodynamicquantities associated to the adsorbed monolayer has been analyzedand discussed in the context of the Lattice-Gas model.