The excitation profile for solitons in trans-${\left(\mathrm{CH}\right)}_x$ was determined by measuring the strength of the photoinduced absorption as a function of the photogeneration source. The results demonstrate soliton photoproduction at energies well below the principal interband absorption edge. These data prove that charged soliton-antisoliton pairs are photogenerated directly (threshold $\hslash \omega =\frac{4\Delta }{\pi }$) assisted by quantum fluctuations in the ground state, as well as indirectly at higher energies ($\hslash \omega >~2\Delta$) via structural relaxation around electron-hole excitations.

• Received 1 August 1983

DOI:https://doi.org/10.1103/PhysRevLett.51.2132