宽频段太赫兹光谱技术的抗坏血酸和硫胺素研究

采用太赫兹时域光谱(THz-TDS)和傅里叶变换红外光谱(FTIR)，测量了L-抗坏血酸与硫胺素在0.10~3.50 THz的光谱特性。给出了两种维生素的分子模型，详细分析比较了抗坏血酸与硫胺素在两种方法测量下吸收光谱的异同。结果表明：利用太赫兹时域光谱和傅里叶红外光谱测得的特征吸收谱在0.70~3.00 THz完全吻合，而在较低频段0.30~0.50 THz，两种样品的傅里叶红外光谱展现了太赫兹时域光谱所没有的特征峰，同时硫胺素样品在8.00~12.00 THz范围内，8.75，8.85，9.00，9.30和10.30 THz出现指纹峰;研究了样品掺杂不同比例聚乙烯粉末时THz吸收光谱的差异，抗坏血酸对太赫兹吸收较弱，总结了两种维生素的折射率曲线与其吸收峰的对应关系;结果对抗坏血酸和硫胺素的分析识别以及维生素太赫兹光谱数据库的建立具有重要参考意义。

Research on L-Ascorbic Acid and Thiamine Based on Wide-Band Terahertz Spectroscopy Technique

We employed terahertz time-domain spectra (THz-TDS) and Fourier transform infrared spectra (FTIR) to measure the terahertz spectroscopy of L-ascorbic acid and thiamine in the frequency region ranging from 0.10 to 3.50 THz. Molecular models of two vitamins have been shown, and based on above two spectroscopies, we compared the differences about the absorption spectra between the L-ascorbic acid and the thiamine. The measured results show that the absorption spectra obtained based on THz-TDS and FTIR are completely consistent in the frequency range of 0.70 to 3.00 THz. New fingerprint peaks obtained by the FTIR in the low frequency region from 0.30 to 0.50 THz in terms of high sensitive silicon bolometer detector, which are not found by the THz-TDS. Furthermore, several bands at 8.75, 8.85, 9.00, 9.30 and 10.30 THz, fingerprint peaks have been found in the frequency region from 8.00 to 12.00 THz for the thiamine sample obtained by the FTIR. Measurement results indicate the absorption spectra depend on the ratio of polyethylene powder mixed with the L-ascorbic acid. L-ascorbic acid has a lower absorption ability at THz band, so pure samples shouldbe used for testing experiment. In addition, we calculated the refractive index for the two samples. This study has important implications for the discriminatory analysis of vitamins and the establishment of vitamin spectroscopy standard database.