Picosecond photoinduced dichroism 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-12, changing to a lower power after ∼50 psec. Although the photoinduced bleaching persists to long times, polarization memory is lost after ∼10-9 sec. The results provide a measurement of the diffusion constant of the charged excitations; 2×10-2 cm2 sec-1 at 300 and 80 K.