Study on Characteristics of Terahertz Spectra of Organic Functional Groups
MA Chun-qian, XU Xiang-dong*, ZOU Rui-jiao*, LIU Yi-ke, HE Qiong, JIANG Ya-dong, HUANG Rui, WEN Yue-jiang, SUN Zi-qiang
State Key Laboratory of Electronic Thin Films and Integrated Devices, Ministry of Education Key Laboratory of Photoelectric Detection & Sensor Integration Technology, School of Optoelectronic Information, University of Electronic Science and Technology of China, Chengdu 610054, China
Abstract：Fourier transform infrared (FTIR) was exploited to measure terahertz (THz) spectra in the wave number range of 30~300 cm-1 for saturated straight chain organic molecules at room temperature. The results reveal that different organic functional groups exhibit different THz spectral characteristics. The absorption peaks of vibration modes of organic crystal lattice locate in high frequency range of THz, while those of vibration modes of intermolecular hydrogen (H) bonds appear in low frequency range of THz. Moreover, a typical absorption peak of intermolecular H bonds caused by saturated straight-chain monohydric alcohol hydroxyl functional groups locates at 57 cm-1, while a characteristic absorption peak of intermolecular hydrogen bonds caused by triacontanoic acid carboxyl functional groups appears at 74 cm-1. The intermolecular H bonds not only result in that the THz absorbing abilities of triacontanol and triacontanoic acid are significantly stronger than that of triacontane, but also cause regular red-shift and blue-shift of the THz absorption peaks of triacontanoic acid, as compared with those of triacontanol. In addition, density functional theory (DFT) B3LYP/6-311G(d,p) basis set was employed to simulate the THz spectra of saturated straight-chain alkane, alkanol and acid, respectively. The simulation results indicate that for the organic molecules with stronger intermolecular H bonds, lower consistent degree of the THz spectrum simulated from monomer molecule with the THz spectrum experimentally measured will occur. Moreover, the simulation results of dimer structures agree well with the measured spectra as compared to those simulated from monomer molecule structures. The results presented in this work are of great significance not only to the study of the THz spectral characteristics of other organic functional groups, but also to the clarification of the vibration modes of organic molecules. Particularly, our results are also helpful for clarifying the THz response theory of organics, and for exploiting the applications of organic materials in THz devices.
马春前，许向东*，邹蕊矫*，刘一客，何 琼，蒋亚东，黄 锐，温粤江，孙自强 . 有机官能团的太赫兹光谱特征研究 [J]. 光谱学与光谱分析, 2015, 35(04): 870-874.
MA Chun-qian, XU Xiang-dong*, ZOU Rui-jiao*, LIU Yi-ke, HE Qiong, JIANG Ya-dong, HUANG Rui, WEN Yue-jiang, SUN Zi-qiang . Study on Characteristics of Terahertz Spectra of Organic Functional Groups . SPECTROSCOPY AND SPECTRAL ANALYSIS, 2015, 35(04): 870-874.
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