Department of Physics, Yonsei University, Wonju, Gangwon-do 220-710, Korea.
J Chem Phys. 2013 Nov 14;139(18):184711. doi: 10.1063/1.4829764.
We have studied the element and orbital-specific electronic structure of thin films of 3,4,9,10-perylene-tetracarboxylic-dianhydride (PTCDA) using a combination of synchrotron radiation-exited resonant x-ray emission spectroscopy, x-ray absorption spectroscopy, x-ray photoelectron spectroscopy, as well as density functional theory calculations. Resonant and non-resonant x-ray emission spectroscopies were used to measure the C and O 2p partial densities of state in PTCDA. Furthermore, resonant x-ray emission at the C and O K-edges is shown to be able to measure the partial densities of states associated with individual atomic sites. The flat molecular orientation of PTCDA on various substrates is explained in terms of the carbonyl O atom acting as a hydrogen-bond acceptor leading to multiple in-plane intermolecular C=O···H-C hydrogen bonding between carbonyl groups and the perylene core of the neighboring PTCDA molecules. We support this conclusion by comparison of our calculations to measurements of the electronic structure using element-, site-, and orbital-selective C and O K-edge resonant x-ray emission spectroscopy, and photoemission spectroscopy.
我们使用同步辐射激发的共振 x 射线发射光谱学、x 射线吸收光谱学、x 射线光电子能谱学以及密度泛函理论计算，研究了 3,4,9,10-苝四羧酸二酐（PTCDA）薄膜的元素和轨道特异性电子结构。共振和非共振 x 射线发射光谱学用于测量 PTCDA 中的 C 和 O 2p 部分态密度。此外，C 和 O K 边缘的共振 x 射线发射被证明能够测量与各个原子位置相关的部分态密度。PTCDA 在各种基底上的平面分子取向可以用羰基 O 原子作为氢键受体来解释，这导致了羰基和相邻 PTCDA 分子的苝核之间的多个平面内分子间 C=O···H-C 氢键。我们通过将我们的计算与使用元素、位置和轨道选择性 C 和 O K 边缘共振 x 射线发射光谱学和光电子能谱学测量的电子结构进行比较，支持了这一结论。
