Femtosecond transient absorption spectroscopy of nanocrystalline polydiacetylene colloids

Tsuyoshi Asahi, Kazumasa Kibisako, Hiroshi Masuhara, Hitoshi Kasai, Hideyuki Katagi, Hidetoshi Oikawa, Hachiro Nakanishi

Research output: Contribution to journalConference articlepeer-review

8 Citations (Scopus)


Femtosecond transient absorption spectral measurements have been performed for size-controlled polydiacetylene microcrystals (30, 100, and 150 nm mean diameter) dispersed in water. Ultrafast relaxation processes within 5 ps after excitation were attributed to formation and decay of self-trapped exciton, which was independent on the size. A time-dependent spectral shift of transient bleaching, corresponding to the stationary excitonic absorption band, was observed in the time region from 10 ps to a few ns. It is explained as a thermalization of absorbed light energy within the microcrystal and the succeeding cooling by comparing transient absorption spectra with temperature difference spectra of the ground state absorption. Size-dependent cooling dynamics of a 'hot' microcrystal was successfully demonstrated; the time constant increases with the crystal size.

Original languageEnglish
Pages (from-to)95-100
Number of pages6
JournalMolecular Crystals and Liquid Crystals
Publication statusPublished - 1998
EventProceedings of the 1998 TAPPI Metered Size Press Forum - New Orleans, LA, USA
Duration: 1998 Apr 301998 May 2


  • Cooling dynamics
  • Femtosecond absorption spectroscopy
  • Microcrystals
  • Polydiacetylene
  • Size dependence


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