Full Picture of Valence Band Structure of Rubrene Single Crystals Probed by Angle-Resolved and Excitation-Energy-Dependent Photoelectron Spectroscopy

The valence band structure of rubrene single crystals was experimentally determined by high-resolution angle-resolved and excitation-energy-dependent photoelectron spectroscopy at room temperature. The energy position of the peak derived from the highest occupied molecular orbital did not depend on the excitation energy, reflecting an absence of energy dispersion along the surface normal direction. A two-dimensional valence band dispersion relation over the surface Brillouin zone obtained by angle-resolved photoemission to three critical points was reproduced excellently by a two-dimensional tight binding approximation. Highly anisotropic values of intermolecular transfer integrals to four adjacent molecules were obtained from the present results. (C) 2012 The Japan Society of Applied Physics

通过室温下高分辨率角分辨和激发能相关的光电子能谱实验确定了红荧烯单晶的价带结构。源于最高占据分子轨道的峰的能量位置不依赖于激发能，这反映了沿表面法线方向没有能量色散。通过角分辨光发射得到的表面布里渊区上到三个临界点的二维价带色散关系通过二维紧束缚近似得到了极好的重现。从目前的结果中获得了到四个相邻分子的分子间转移积分的高度各向异性值。（C）2012日本应用物理学会