Inelastic Electron Scattering Spectroscopy of Intercalated Graphite and Polyacetylene

Abstract

Synthetic metals can be made by intercalating a wide variety of atoms and molecules between the layers of graphite. The increase in conductivity over that of pristine graphite is 1–2 orders of magnitude. Some highly conjugated polymers, such as polyacetylene, will react with some of the graphite intercalants to produce synthetic metals also, but in these materials the increase in conductivity is 12 orders of magnitude (1). Although the structure of doped polyacetylene is not nearly as crystalline and well understood as that of the graphite compounds, there is evidence that the dopants occupy planes similar to graphite intercalants (2). In addition, the increase in conductivity in these two classes of synthetic metals is certainly associated with the charge transfer which accompanies the intercalation reaction. Thus, the nature of the donor-acceptor interaction in these materials is of prime importance. In a number of recent experiments (3–6), we have attempted to quantitatively measure the change in the electronic structure of graphite when it is reacted with acceptor intercalants such as FeCl₅, AsF₅ and SbCl₅.