Ultrafast electronic and acoustic effects in conducting polymers

The polarized picosecond pump and probe technique with 50 fsec resolution has been used to generate and detect electronic excitations and propagation of ultrasonic phonons in thin films of oriented and unoriented polyacetylene and polythiophene. We found that the photoexcitations are instantaneously generated followed by a power law decay, which is interpreted as fast geminate recombination; only up to about 2% of the intrachain carriers are able to escape fast recombination.