Zheng Ren-Hui, Wei Wen-Mei, Yan Ya-Ming
Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Institute of Chemistry, Chinese Academy of Sciences, Zhongguancun, Beijing 100190, People's Republic of China.
Department of Chemistry, School of Basic Medical Science, Anhui Medical University, Hefei, Anhui 230032, People's Republic of China.
Spectrochim Acta A Mol Biomol Spectrosc. 2020 Nov 5;241:118659. doi: 10.1016/j.saa.2020.118659. Epub 2020 Jul 2.
Using quantum chemistry computations TDDFT//B3LYP/6-31G(d), we study resonance Raman spectra of the Q band for meso-tetrakis(3,5-di-tertiarybutylphenyl)-porphyrin (HTBPP) molecule due to the Franck-Condon and non-Condon mechanisms including the Herzberg-Teller and second-order Herzberg-Teller terms. Generally, the Herzberg-Teller terms are large. However, for some vibrational modes, the second-order Herzberg-Teller terms are the strongest and dominate resonance Raman spectra, which may also impact on fluorescence and absorption spectra. Hence, the Taylor expansion of the electric dipole transition moment with respect to the normal coordinates at the equilibrium structure of the ground electronic state may not converge for HTBPP. A method to solve this problem is suggested.
采用量子化学计算TDDFT//B3LYP/6-31G(d)，我们研究了中位四(3,5-二叔丁基苯基)卟啉(HTBPP)分子Q带的共振拉曼光谱，该光谱源于弗兰克-康登和非康登机制，包括赫兹伯格-泰勒项和二阶赫兹伯格-泰勒项。一般来说，赫兹伯格-泰勒项较大。然而，对于某些振动模式，二阶赫兹伯格-泰勒项最强并主导共振拉曼光谱，这也可能影响荧光和吸收光谱。因此，在基态电子态平衡结构下，电偶极跃迁矩相对于正常坐标的泰勒展开式对于HTBPP可能不收敛。本文提出了一种解决该问题的方法。
