On the transfer of excitation energy in poly(P-phenylenevinylene) as studied by fluorescence depolarization
- Measurements of polarized excitation and fluorescence spectra were carried out with thin films of PPV and with films of oligomer model compounds in a polystyrene matrix. The degree of fluorrescece polarization r and its spectral dependence are discussed with respect to the transfer of excitation energy and the mutual alignment of the flurophores. In contrast to the behaviour of conventional aromatic polymers, the value of r is non-zero in isotropic PPV and depends on preparation (up to r = 0.25 at λexc = 460 nm and λflu = 555 nm). r can be nearly as high as in the dilute solid solution of the oligomers. This is easily understood if the PPV segments are highly aligned in the distance range of energy transfer.