Excitation dynamics in disubstituted polyacetylene

We studied the excitation dynamics in films of disubstituted polyacetylene, a degenerate groundstate conjugated polymer, using psec transient and stea dy-state spectroscopies. The polymer is found to support charged and neutra l topological soliton excitations concurrent with a strong intrinsic photol uminescence band with quantum efficiency, eta similar or equal to 50%. This leads to stimulated emission in thin films and lasing in cylindrical mu ca vities. The seeming contradiction of a degenerate ground-state polymer with high eta is explained by the lowest excited-state ordering.