Evidence of a midgap band in the density of states of acceptor-dopedtrans-polyacetylene by elastic electron tunneling

Tunnel junctions between doped polyacetylene and an oxidized aluminum electrode have been realized with a point contact geometry. The conductance $\frac{\mathrm{dI}\left(V\right)\mathrm{}}{\mathrm{dt}}$ has been measured and interpretated in relation to the electron density of states of doped polyacetylene and shows predicted features of the metal-insulator transition of doped ${\left(\mathrm{CH}\right)}_x$. From our data, numerical energy values are obtained in agreement with the value of the Peierls gap and the midgap soliton band.