Critical behavior of interacting monomers adsorbed on one-dimensional channels arranged in a triangular cross-sectional structure: mixed interactions along and across the channels.

Monte Carlo simulations and finite-size scaling analysis have been carried out to study the critical behavior in a submonolayer lattice-gas which mimics a nanoporous environment. In this model, the adsorbent is modeled as one-dimensional channels of equivalent adsorption sites arranged in a triangular cross-sectional structure. Two kinds of lateral interaction energies have been considered: (1) w(L) interaction energy between nearest-neighbor particles adsorbed along a single channel and (2) w(T) interaction energy between particles adsorbed across nearest-neighbor channels. We focus on the case of repulsive transverse (w(T)>0) and attractive longitudinal (w(L)<0) lateral interactions, where a rich variety of structural orderings are observed in the adlayer depending on the value of the parameters k(B)T/w(T) (being k(B) the Boltzmann constant) and w(L)/w(T). The results reveal the existence of a first-order phase transition in the adlayer between a low-temperature "condensed" phase and a high-temperature "disordered" phase.