Ordering transition of gases adsorbed on aC60surface: Monte Carlo simulations and lattice-gas models

Abstract

A monolayer of C 60 molecules on a flat surface provides an unusual substrate for the adsorption of simple gases. Both the lattice constant and the corrugation are larger than is typical of most traditional surfaces. These differences give rise to different phenomena, such as unusual commensurate phases. This paper discusses the ordering transition of various gases corresponding to the filling of the honeycomb array of threefold coordinated hollow sites located between C 60 molecules. That transition is investigated with Monte Carlo simulations and analytical ͑lattice-gas͒ models. The value of the resulting transition temperature ͑T c ͒ depends on the form assumed for the long-range interaction and the role of many-body effects, i.e., screening, due to gas molecules' close proximity to the C 60 layer. The effect of three-body interactions is found to be large in all cases considered.We have used grand canonical Monte Carlo simulations to predict the adsorption behavior of Xe on the C 60 surface. The method, identical to that used in our previous study of this problem, 10 requires two input potentials. One is the Xe-Xe interaction, for which we have used the venerable Lennard-Jones ͑LJ͒ interaction, with parameters = 4.1 Å and / k B = 221 K, respectively. The other is the Xe-C 60 interaction, which we take to have the form PHYSICAL REVIEW B 78, 205417 ͑2008͒

Ordered phases of ethylene adsorbed on charged fullerenes and their aggregates

“…There are several reasons to expect significant differences in the properties of ethylene adsorbed on graphite, and fullerene. First, as seen in the current work, ethylene on C 60 strongly prefers to form a commensurate phase because the corrugation is enhanced on convex surfaces [25,26] whereas commensurate phases on graphite escaped detection in all but Eden and Fain’s electron diffraction work [16,17] . Commensurate phases on graphite also failed to appear in molecular dynamics simulations [7,79] , even when the strength of the corrugation was deliberately increased [13,15] .…”

“…Experiments involving bundles of nanotubes inevitably suffer from the non-uniformity of tubes and the presence of defects; these difficulties are avoided in the current experiments involving C 60 . Also of interest are the differences between the surface of free fullerenes and planar graphite (or graphene) because the curvature of the substrate decreases the adsorption energies while it enhances the corrugation and increases the separation between adatoms at adjacent hollow sites [25,26] .…”

Cold physics and chemistry: Collisions, ionization and reactions inside helium nanodroplets close to zero K

“…Furthermore, fullerene aggregates offer two other types of adsorption sites with much larger corrugation, namely sites in the groove between two adjacent fullerenes (analogous to groove sites between parallel nanotubes [564]), and at dimples between three adjacent C60 (analogous to the preferred sites on the surface of a C60 crystal [561]). The interplay between these corrugations leads to several interesting phenomena [565,566].…”

Structures, Energetics, and Dynamics of Helium Adsorbed on Isolated Fullerene Ions

“…An interesting feature common to nanotubes and fullerite surfaces is the existence of two kinds of corrugation, a strong one caused by the curved surfaces plus a weak one due to the hexagonal and, for fullerenes, pentagonal facets of the carbon network. The interplay between these two corrugations leads to interesting phenomena in theoretical studies [5,8], but they are difficult to observe experimentally because of the unavoidable distribution of tube diameters and rotational orientation [9].…”

“…A closepacked layer of C 60 offers deep potential minima that form a honeycomb lattice with a spacing of 5.8 Å ; Monte Carlo simulations predict an ordered phase of helium at low temperature [5].…”