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  Local Chain Dynamics Studied by
  the Fluorescence Depolarization Method


Fluorescent molecules such as anthracence has an electronic transition moment M. The dye molecule is selectively excited by the absorption of the linearly polarized light and emits the fluorescence polarized in the direction of M. Therefore, when the dye molecule (i.e. M) is fixed, the fluorescence is highly polarized. However, the dipole M rotates in the fluorescence lifetime because of the Brownian motion, resulting in the depolarization (animated cartoons for slow and fast motion). Thus, the degree of polarization reflects the mobility of the dye molecule.
The most advantage of this technique is that the time-dependent fluroescence anisotropy ratio r(t) is equivalent to the orientational auto-correlation function of the transition vector for the probe chromophore. The time-resolved fluorescence depolarization method directly measures the molecular motion in the time scale of 100 ps - 100 ns. Moreover, the selective introduction of the fluorescence probe to the polymer chain enables one to discuss the dynamics of the specific site in the polymer chain. The fluorescence depolarization technique is one of the powerful tools for the investigation of the polymer dynamics.

1. Local Motion of Polymer Chain in Dilute Solutions (Effect of side chain, stereo-regularity, solvent quality, and so on)
2. Dynamics of Polymer Stereo-Complex
3. Dynamics of Network Chain of Polymer Gels
4. Local Motion of Graft Chain on Solid Surfaces
5. olecular Dynamics Simulation

Selected Publications
1. J. Horinaka, H. Aoki, S. Ito, M. Yamamoto, Polym. J., 31 , 172 (1999).
2. J. Horinaka, S. Ito, M. Yamamoto, T. Matsuda, Comp. Theor. Polym. Sci., 10, 365 (2000).
3. H. Aoki, J. Horinaka, S. Ito, M. Yamamoto, H. Katayama, M. Kamigaito, M. Sawamoto, Polym. J., 33, 464 (2001).
4. H. Aoki, M. Kitamura, S. Ito, Macromolecules, 41, 285-287 (2008).

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