Core Excitons in Polyacetylene: Evidence for a Closed-Gap Metallic State

Abstract

The excitation spectra of carbon $1s$ core electrons into the empty conduction-band states of polyacetylene and polyacetylene doped to saturation with As${\mathrm{F}}_5$ show that the electronic structure of the heavily doped samples is not that of a degenerate semiconductor, but rather that of a simple metal in which the original semiconducting band gap has been closed.