Photoexcitation dynamics in polyacetylene probed by transient photoinduced resonance raman scattering

We have measured photoexcitation dynamics in the picosecond time domain in fully {ital trans} and partially isomerized (CH){sub {ital x}} and (CD){sub {ital x}} films with different {ital cis}/{ital trans} content ratios, using the technique of transient photoinduced resonant Raman scattering. Following the distinctively different decay kinetics of {ital cis} and {ital trans} resonantly enhanced vibrations, we observed an intersystem crossing of photoexcitations from {ital cis} to {ital trans} segments which is dominated by a diffusion process in the {ital cis} segments, with a time constant between 24 and 215 ps depending on the {ital cis}/{ital trans} ratio.