MISC

2008年5月

Simultaneous measurement of electronic and vibrational dynamics to clarify a geometrical relaxation process in a conjugated polymer

PHYSICAL REVIEW B
  • Juan Du
  • ,
  • Zhuan Wang
  • ,
  • Wei Feng
  • ,
  • Katsumi Yoshino
  • ,
  • Takayoshi Kobayashi

77
19
開始ページ
195205
終了ページ
記述言語
英語
掲載種別
DOI
10.1103/PhysRevB.77.195205
出版者・発行元
AMER PHYSICAL SOC

The real-time vibrational spectroscopy was utilized to obtain both electronic and vibrational dynamics in a conjugated polymer under the same excitation and probing condition by using the same sample and observing at the same time. Most of the conjugated polymers are in an amorphous phase, in which there is a relatively broad distribution of chain length, conjugation length, and degree of interaction strength between neighboring chains. Because of the varieties, a simultaneous measurement of electronic and vibrational dynamics in a broad spectral range is considered to be most powerful to study such systems as conjugated polymers. In the present paper, we performed this type of experiment of the simultaneous probing of electronic and vibrational relaxations at 128 wavelengths. The sample studied here is an amino-moiety-containing conjugated polymer, poly{[3-hexylthiophene-2,5-diyl]-[p-dimethylaminobenzylidenequinoidmethene]} (PHTDMABQ), whose monomer is a derivative of a thiophene oligomer. The light source is a few-cycle pulse laser with an ultimate time resolution of 0.2 fs in the visible and near IR ranges. The data containing both electronic relaxation and vibrational dynamics were analyzed to obtain a more reliable relaxation mechanism of the excitations than a combination of individual studies of electronic and vibrational relaxations. By utilizing the ultrafast pump-probe spectroscopic system, we could identify the exciton state with a pi-electron delocalized in benzilidene ring. In the polymer PHTDMABQ, the geometrical relaxation from the free exciton to the exciton polaron takes place in 60-100 fs. This time is close to that observed in several polydiacetylenes previously reported. The C-C single bond stretching frequencies of the free exciton and exciton polaron are about 1300 and 1350 cm(-1). The coherent molecular vibration after the geometrical relaxation is considered to be a kind of reaction induced coherence. This coherent vibration decays with the time constant of about 450 fs.

Web of Science ® 被引用回数 : 19

リンク情報
DOI
https://doi.org/10.1103/PhysRevB.77.195205
Web of Science
https://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=JSTA_CEL&SrcApp=J_Gate_JST&DestLinkType=FullRecord&KeyUT=WOS:000256971600071&DestApp=WOS_CPL
ID情報
  • DOI : 10.1103/PhysRevB.77.195205
  • ISSN : 1098-0121
  • Web of Science ID : WOS:000256971600071

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