Vaughan Helen L, Monkman Andrew P, Pålsson Lars-Olof, Nehls Benjamin S, Farrell Tony, Scherf Ullrich
OEM Research Group, Department of Physics, University of Durham, Durham DH1 3LE, England.
J Chem Phys. 2008 Jan 28;128(4):044709. doi: 10.1063/1.2822273.
Two ladder-type polymers have been examined using polarized optical absorption and fluorescence spectroscopy in solution and solid state. The fluorescence anisotropy excitation spectra of ladder-type methyl-substituted poly(para-phenylene) and poly(naphthylene-phenylene) follow their absorption profiles, contrary to the typical behavior in other conjugated polymers, which show excitation wavelength dependent anisotropy until the onset of the typical red edge effect. Using Raman microscopy and linear dichroism of aligned stretched polyethylene films containing the ladder polymer, it has been found that the orientation of the absorption transition dipole moment is dependent on the conjugation length. The transition dipole of the shorter conjugation lengths of the distribution is localized approximately 7 degrees off axis, and that of the longer conjugation lengths is delocalized along the chain.
已使用溶液和固态中的偏振光吸收和荧光光谱法对两种梯型聚合物进行了研究。梯型甲基取代聚对苯撑和聚萘撑苯撑的荧光各向异性激发光谱遵循其吸收谱，这与其他共轭聚合物的典型行为相反，其他共轭聚合物在典型的红边效应开始之前显示出与激发波长相关的各向异性。通过使用含有梯型聚合物的取向拉伸聚乙烯薄膜的拉曼显微镜和线性二色性，已发现吸收跃迁偶极矩的取向取决于共轭长度。分布中较短共轭长度的跃迁偶极大约偏离轴7度定位，而较长共轭长度的跃迁偶极则沿链离域。
