Ultrafast relaxation processes of solitons, polarons, and self-trapped excitons in MX-chain

Ultrafast relaxation processes of photoexcited states of a quasi-one-dimensional halogen-bridged mixed-valence metal complex [Pt(en)2][Pt(en)2Cl2](PF6)4 have been investigated by femtosecond transient absorption spectra measurements. It has been found that a considerable part of the neutral soliton pairs is generated directly from photogenerated charge transfer excitons. Charged soliton pairs have been found to be generated from free electron–hole pairs. The rise time and the decay time of the charged soliton absorption band are 2.2 and 6.5 ps, respectively. The polaron pairs are generated from free electron–hole pairs within time resolution.