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. Author manuscript; available in PMC: 2014 Aug 7.
Published in final edited form as: J Am Chem Soc. 2013 Jul 29;135(31):11453–11456. doi: 10.1021/ja404719f

Figure 3.

Figure 3

Polarization sensitivity of polymer nanoparticle. The fluorescent PFBT polymer is held within the hydrophobic core of the polymer nanoparticle. Upon excitation with polarized light (A) intramolecular exciton transfer quickly directs fluorescence to chromophores within the polymer chain where fluorescent emission is favored. In (B), a time-resolved fluorescence anisotropy decay (purple) is overlaid with the fluorescence lifetime decay of PFBT nanoparticles, showing that emission depolarization occurs more quickly than fluorescence decay. Depolarization also occurs much faster than the calculated rotational correlation time of a 10-nm-diameter particle in water. Although the emission is polarized, the direction of polarized emission is independent of excitation polarization and different for each nanoparticle.