Cao Bing-Hua, Zhang Guang-Xin, Hou Di-Bo, Huang Ping-Jie, Zhou Ze-Kui
State Key Lab of Industrial Control Technology, Department of Control Science and Engineering, Zhejiang University, Hangzhou 310027, China.
Guang Pu Xue Yu Guang Pu Fen Xi. 2009 Jul;29(7):1729-31.
The present paper reports the theoretical and experimental vibrational frequencies of L-ascorbic acid in the frequency range from 0.2 to 2.4 THz respectively. The vibrational frequencies of L-ascorbic acid in the THz range were simulated by Becke-3-Lee-Yang-Parr (B3LYP) algorithm of density functional theory. Simultaneously, the absorption and refractive index spectra of L-ascorbic acid were obtained using terahertz time-domain spectroscopy (THz-TDS). Based on the results from density functional calculations, the observed vibrational peaks were assigned with the aid of Gaussian View 3.07. Finally, the tera-hertz absorption spectra of tablets of vitamin C were compared with those of L-ascorbic acid. It was found that L-ascorbic acid had some distinct fingerprint spectra in the THz region and the theoretical results were in good agreement with the experimental results. The observed vibrational peaks were induced jointly by the intramolecular and intermolecular vibrations. The absorption peaks of L-ascorbic acid could be observed in the absorption spectra of the tablets of vitamin C. Our research is helpful to understanding the role of L-ascorbic acid in biological reactions. Still, the research results show the potential of the application of THz-TDS in the quantification of L-ascorbic acid.
本文分别报道了L-抗坏血酸在0.2至2.4太赫兹频率范围内的理论和实验振动频率。采用密度泛函理论的Becke-3-Lee-Yang-Parr（B3LYP）算法模拟了L-抗坏血酸在太赫兹范围内的振动频率。同时，利用太赫兹时域光谱（THz-TDS）获得了L-抗坏血酸的吸收光谱和折射率光谱。基于密度泛函计算结果，借助Gaussian View 3.07对观测到的振动峰进行了归属。最后，将维生素C片剂的太赫兹吸收光谱与L-抗坏血酸的太赫兹吸收光谱进行了比较。结果发现，L-抗坏血酸在太赫兹区域有一些独特的指纹光谱，理论结果与实验结果吻合良好。观测到的振动峰是由分子内和分子间振动共同引起的。在维生素C片剂的吸收光谱中可以观察到L-抗坏血酸的吸收峰。我们的研究有助于理解L-抗坏血酸在生物反应中的作用。此外，研究结果表明太赫兹时域光谱在L-抗坏血酸定量分析方面具有应用潜力。
