Photoexcitations in pernigraniline: Ring-torsional polarons and bond-order solitons

Abstract

We report the near-steady-state and long-time photoinduced spectroscopies of pernigraniline base, a novel Peierls ground-state polymer with multiple order parameters. Two kinds of defects are distinguished by differing time domains, ir-active vibrations, and light-induced electron spin resonance. The short-lived defect has a lifetime of msec scale, defect mass of \ensuremath{\sim}5${\mathit{m}}_{\mathit{e}}$, and is spinless; in contrast, the long-lived defect (mass \ensuremath{\sim}300${\mathit{m}}_{\mathit{e}}$) has a lifetime of greater than several hours at low temperatures, and spin 1/2. We propose that the short-lived excitation is a soliton defect in the bond-length order parameter, while the long-lived excitation is a polaronlike defect in the ring-torsion-angle order parameter.