Yashchuk V. The dynamics of electronic-vibrational excitations in macromolecules

The dissertation is devoted to the investigations of dynamics of electronic-vibrational excitations in organic macromolecules containing nonconjugated p-electron systems. The results of investigations of the nature of absorbtion and luminescence centres, the electronic and vibration energy transfer in organic macromolecules are examined and analyzed (phenyl-, carbazole-, benzcarbazole-, benzophenone-containing polymers and copolymers as well as DNA macromolecules were studied). Absorbtion spectra of polymers and copolymers which were investigated are near the absorption spectra of low-molecular compounds and manifest the additive (independent) contribution of intramolecular impurities or copolymer species. It allows to modify the macromolecules composition without essential influence on macromolecular basic unit energy sites. Such modifications give a possibility to create the model macromolecules for unique photophysical experiments. Fluorescence spectra of p-electron-containing polymers are rather co mplicated and in a number of cases are different from fluorescence spectra of their low molecular analogies. At 77 K the main maxima (0-1) of fluorescence spectra of homopolymers polyvinylcarbazole (PVCa), polyvinyl-5benzocarbazole (PV5BCa), polyvinyl-7benzocarbazole (PV7BCa), polyvinyl-11benzocarbazole (PV11BCa) solutions are near the main maxima of low molecular compounds but in spectra of these polymers the first short-wave maxima which could correspond to the short-wave maxima (0-0) of a low molecular model compound are absent. To our point of view (contrary to well-known version of "excimers-II") a short-wave band is connected with the emission of polymer cells (monomer units), but the shape of its spectrum is disturbed by intramolecular reabsorption. So, only one type of excimers ("classical", long-wave) contributes in total emission of chromophore-containing polymers. Phosphorescence. Short-wave phosphorescence with structural "monomer-like" spectrum is observed (below ~ 40 K) for homopolymers (solutio n, powders and films). Above this temperature an unstructured red-shifted band appears. This band was assigned by other investigators to emission of triplet excimers - as analogy to singlet excimers. It was found in present work that long-wave structureless phosphorescence of aromatic-containing polymers is connected with products of oxidation.