Photochemical hole burning in nanostructured polymers

2019-07-05 23:46:00

DNA systems showed hole phonon

责任者: Machida, Shinjiro;Horie, Kazuyuki 单位: Dept. of Polymer Science/Engineering, Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585, Japan 来源出处: Kobunshi Ronbunshu,2002,59(12):725-733 摘要: We performed photochemical hole burning spectroscopy with several kinds of nanostructured polymer systems: a DNA-lipid complex, unimacromolecular micelles, dendrimer porphyrins, and mutated proteins. Nanoscopic environments around the dye, including structural relaxation at low temperatures and electron-phonon interactions are evaluated for these systems. DNA-lipid complex film showed marked hole broadening but no hole filling at 40 K. We attributed this result to the intercalation of porphyrin molecules into the double helix of DNA. Molecular weight dependence of phonon frequency of the unimacromolecular micelle systems showed that the electron-phonon interaction is effective within 2.3 nm around the dye. Dendrimer porphyrin neat films showed sharp holes at 20 K. Hole areas of dendrimer porphyrins of higher generation showed better temperature stability, reflecting the the surface mobility. A mutated cytochrome b562, which has aspartic acid instead of asparagine in the wild type, showed stepwise hole broadening at 35 K. This was the first observation of a mutual relationship between the location of the site where the structural relaxation occurs and the increase in holewidth. 关键词: Biopolymers;Photochemical reactions;Nanostructured materials;Dendrimers;Dyes;Phonons;Nanostructured polymer systems