VANDERWAALS BINDING OF FULLERENES TO A GRAPHITE PLANE

We develop a model that predicts the potential energy function W(R) of a spherical fullerene, C(N), near a graphite surface. R is the distance between the fullerene center of mass and the surface. The model is based on summing all the interactions between the C atoms in the fullerene and those on a graphite sheet. The atom-atom potential employed is a Lennard-Jones 12-6 potential with parameters chosen from previous treatments of graphite and of C60(S). The binding energy is suprisingly large, varying between 15 and 19 kcal/mol for C60 depending on the potential, and scales approximately as N1/2. W(R) is used to determine the force constant and fundamental frequency, as well as the Arrhenius expression A exp(-E(a)/kT), for desorption of the C(N) from the graphite surface. This information can be used to determine relative desorption rates as a function of temperature for fullerenes that are more round than cylindrical. We describe and predict the results of a feasible experiment that would measure the temperature-programmed desorption of fullerenes from a graphite surface.