Excited-State dynamics of conjugated polycarbosilane oligomers with branched dimethyl or diphenyl group
✍ Scribed by I.-W. Hwang; N. W. Song; D. Kim; Y. T. Park; Y.-R. Kim
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- English
- Weight
- 173 KB
- Volume
- 37
- Category
- Article
- ISSN
- 0887-6266
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✦ Synopsis
Dimethyl or diphenyl branched conjugated polycarbosilane oligomers in solutions, including poly [[1,4-bis(thiophenyl)
and poly [[1,4-bis(phenyl)buta-1,3-diyne]-alt-(diphenylsilane)], were investigated by steady-state and picosecond time-resolved spectroscopies to elucidate the effect of silicon-atom introduction into the -conjugated copolymer backbone and the substitution of the aromatic phenyl group on the silicon atom. The introduction of silicon atoms into -conjugated copolymer backbones induces slow decay emission components with lifetimes of about 450 ps in addition to -* local excitedstate relaxations in the time-resolved fluorescence decay profiles. The diphenyls, which are branched in the silicon atoms, bring about broad, structureless emission bands in the low-frequency region of the steady-state fluorescence spectra. However, such broad bands do not occur in the case of dimethyl branched conjugated polycarbosilane oligomers. The time-resolved and solvent-dependent studies of these bands imply that the excited-state dynamics of diphenyl branched conjugated polycarbosilane oligomers can be related to an intramolecular charge-transfer dynamics through an inductive and (d-p) -conjugation effect between the -conjugated backbone and the branched phenyl ring.