Picosecond photoinduced optical anisotropy in trans-(CH)x : direct measurement of soliton diffusion

Photoinduced dichroism caused by bleaching of the interband transition in trans - (CH)X was observed in the picosecond time domain. The bleaching is induced instantaneously and decays with time as t - 1 / 2 , changing to a lower power after ~ 50 ps. Although the photoinduced bleaching persists to long times, polarization memory is lost after ~ 10-9s. The results provide a measurement of the diffusion constant of the charged excitations; D ≈ 2 x 10-2 cm2 s - 1 at 300K and 80K.