Hinderhofer Alexander, Heinemeyer Ute, Gerlach Alexander, Kowarik Stefan, Jacobs Robert M J, Sakamoto Youichi, Suzuki Toshiyasu, Schreiber Frank
Institut für Angewandte Physik, Universität Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany.
J Chem Phys. 2007 Nov 21;127(19):194705. doi: 10.1063/1.2786992.
The optical properties of pentacene (PEN) and perfluoropentacene (PFP) thin films on various SiO(2) substrates were studied using variable angle spectroscopic ellipsometry. Structural characterization was performed using x-ray reflectivity and atomic force microscopy. A uniaxial model with the optic axis normal to the sample surface was used to analyze the ellipsometry data. A strong optical anisotropy was observed, and enabled the direction of the transition dipole of the absorption bands to be determined. Furthermore, comparison of the optical constants of PEN and PFP thin films with the absorption spectra of the monomers in solution shows significant changes due to the crystalline environment. Relative to the monomer spectrum, the highest occupied molecular orbital to lowest unoccupied molecular orbital transition observed in PEN (PFP) thin film is reduced by 210 meV (280 meV). A second absorption band in the PFP thin film shows a slight blueshift (40 meV) compared to the spectrum of the monomer with its transition dipole perpendicular to that of the first absorption band.
使用可变角度光谱椭偏仪研究了并五苯（PEN）和全氟并五苯（PFP）薄膜在各种SiO₂衬底上的光学性质。使用X射线反射率和原子力显微镜进行结构表征。采用光轴垂直于样品表面的单轴模型分析椭偏数据。观察到强烈的光学各向异性，并且能够确定吸收带跃迁偶极矩的方向。此外，将PEN和PFP薄膜的光学常数与溶液中单体的吸收光谱进行比较，结果表明由于晶体环境的影响出现了显著变化。相对于单体光谱，在PEN（PFP）薄膜中观察到的最高占据分子轨道到最低未占据分子轨道的跃迁降低了210毫电子伏特（280毫电子伏特）。与单体光谱相比，PFP薄膜中的第二个吸收带出现了轻微蓝移（40毫电子伏特），其跃迁偶极矩与第一个吸收带的跃迁偶极矩垂直。
