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Proceedings Paper

Ultrafast nonlinear optical properties of J-aggregates and new preparation method of oriented films at room temperature
Author(s): Kazuhiko Misawa; Kaoru Minoshima; Hiroshi Ono; Makoto Taiji; Takayoshi Kobayashi
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Paper Abstract

Time-resolved difference absorption spectra of J-aggregates in ethyleneglycol/water glass were measured by femtosecond pump- probe spectroscopy. the induced absorption near the J-band at 20 K was assigned to the transitions from n-exciton states to (n + 1)-exciton states (n >= 1). The decay time of the n(>= 2)-exciton states is determined to be about 200 fs. For applications of the J-aggregates as nonlinear optical deices, we present a new fabrication method, called vertical spin-coating, to prepare highly oriented 1D J-aggregates dispersed in polymer films. The films are stable even at room temperature. Linear dichroic spectra of the oriented J-aggregate of 1,1'-diethyl- 2,2'-quinocyanine bromide were measured. The dichroic ratio at the peak of J-band was 5 to 10, depending on the preparation conditions. Precise measurement of the dichroism at the J-band revealed that the J-band is composed of two bands with transition dipole moment perpendicular to each other. Large change in a static dipole moment upon electronic excitation was unexpectedly observed in the oriented J-aggregates by electromodulation spectroscopy. The difference absorption spectra due to the Kerr effect were induced by changes in a static dipole moment and a polarizability. The change in the static dipole moment associated with the transition from the ground state to the exciton state were measured with the applied AC field of Hz and the polarization parallel and perpendicular to the 1D axis of the oriented J-aggregates.

Paper Details

Date Published: 2 June 1994
PDF: 15 pages
Proc. SPIE 2144, Advanced Photonics Materials for Information Technology, (2 June 1994); doi: 10.1117/12.177223
Show Author Affiliations
Kazuhiko Misawa, Univ. of Tokyo (Japan)
Kaoru Minoshima, Univ. of Tokyo (Japan)
Hiroshi Ono, Univ. of Tokyo (Japan)
Makoto Taiji, Univ. of Tokyo (Japan)
Takayoshi Kobayashi, Univ. of Tokyo (Japan)

Published in SPIE Proceedings Vol. 2144:
Advanced Photonics Materials for Information Technology
Shahab Etemad, Editor(s)

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