JIANG Ling1, LI Miao1, LI Chun1, SUN Hai-jun2, XU Li2, LIU Yun-fei*
1. College of Information Science and Technology, Nanjing Forestry University, Nanjing 210037, China 2. Advanced Analysis and Testing Center, Nanjing Forestry University, Nanjing 210037, China
Abstract：Terahertz (THz) absorption spectra of the biotin and pyridoxine were studied using Fourier transform infrared spectroscopy (FTIR) at room temperature. These spectra exhibit enhanced absorption in THz range because of strong intramolecular and intermolecular vibration modes. In the experiment, the samples were mixed with high density polyethylene powder, which was used as spectrophotometric grid. The absorption spectra show worse consistency at higher frequencies for the high ratio of the samples to polyethylene. It indicates that the absorbance of the biotin and pyridoxine increased with frequency. Molecular vibrational spectral calculations based on density functional theory (DFT) show strong correlation with the experiment. We investigated the absorption spectra of isolated molecules (single molecule, two molecules, three molecules) and unit cell of crystal to clarify the mechanism of the spectra change due to intramolecular and intermolecular vibration and rotation.
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