The polarized absorption spectra of crystalline pentacene are obtained for excitation normal to the ab herringbone plane by measuring transmitted light in ultrathin crystals. The spectral line shapes for excitation polarized along b and orthogonal to b are analyzed theoretically using a Holstein-like Hamiltonian which includes both Frenkel and charge transfer (CT) excitons represented in a multiparticle basis set. The model agrees with prior estimates regarding the strong CT contribution (≈45%) of the exciton responsible for the b-polarized lower Davydov component. The polarization resolution allows one to also establish the nature of the upper Davydov component, which is found to contain far less CT content (≈15%), as well as the natures of the higher-energy vibronic excitons, which are found to consist of a complex mixture of Frenkel one- and two-particle states and CT excitons. Generally, the spectrum polarized along b displays J-aggregate-like vibronic signatures while the spectrum polarized orthogonal to b displays H-aggregate-like vibronic signatures. The assignment is entirely consistent with the calculated exciton band dispersions which agree well with the measured ones.

中文翻译：

---

结晶并五苯中的偏振吸收：理论与实验

通过测量超薄晶体中的透射光，获得并五苯晶体的吸收光谱，用于激发垂直于ab人字形平面的光。谱线形状为沿着激发极化b和正交b分析理论上使用荷斯坦状哈密顿其中既包括弗伦凯尔并在多粒子基组表示的电荷转移（CT）激子。该模型与先前估计有关，激元的强CT贡献（≈45％）与b有关。-极化的下达维多夫分量。极化分辨率使人们还可以确定上部达维多夫分量的性质，发现该分量包含更少的CT含量（≈15％），以及较高能量的激子激子的性质，该激子由下列组成： Frenkel一粒子态和两粒子态与CT激子的复杂混合物。通常，沿b偏振的光谱显示J型聚集体的振动信号，而正交于b偏振的光谱显示H型聚集体的振动信号。该分配与计算的激子能带色散完全一致，该激子能带色散与测量的激子能带色散非常吻合。