Electron trapping and transport by supersonic solitons in one-dimensional systems

A one-dimensional chain of ions or molecules and electrons described by a Fr\"ohlich-type Hamiltonian with quartic phonon anharmonicities is investigated. It is shown that the anharmonic lattice supports supersonic solitons which under favorable circumstances may trap electrons and transport them along the lattice. For σ≡d/l~0.1, where d is the lattice constant and l is the spatial extent of the soliton, rough estimates give electron trapping energies in the meV range. They imply a useful temperature range, up to tens of degrees K, for observing the new effect. The activation energy of a lattice soliton is proportional to the molecular mass and is therefore quite high ({~} 1 eV) for typical quasi-one-dimensional organic systems.