STRUCTURAL-PROPERTIES OF ORIENTED POLYDIACETYLENES - AFM AND TIME-RESOLVED SPECTROSCOPY CHARACTERIZATIONS

We report a new approach for the growing of polydiacetylene thin films which leads to better oriented samples as seen by atomic force micros copy (AFM) imaging, as well as static and lime-resolved optical spectr oscopy. With these two techniques, we characterized the morphology and structure of the films as well as the intramolecular relaxation times . The linear optical characterization of poly[ 1,6-di(N-carbazolyl)-2, 4-hexadiyne] (pDCH) samples, grown on a hot crystalline substrate, sho ws a significant red shift of the excitonic pi-->pi transition. The d ynamical measurements allow the determination of the relaxation mechan isms of the pDCH chain. Two types of mechanisms have been distinguishe d: the coherent electronic dephasing and the excitonic population rela xation. The dynamics of both processes is influenced by the structural properties of the polymer backbone. This study suggests that the qual ity of the epitaxial deposition is important for the determination of the intrinsic dynamical properties of the polymer materials.