DNA碱基分子胞嘧啶和胸腺嘧啶的太赫兹光谱研究

利用太赫兹时域光谱技术获得了DNA碱基分子胞嘧啶和胸腺嘧啶在0.1―3.5 THz的特征吸收谱，发现胞嘧啶在2.53 THz的特征吸收细节信息。采用考虑了周期性边界条件的赝势平面波密度泛函方法对胞嘧啶分子晶体进行了结构优化和晶格动力学计算，模拟重现其太赫兹特征吸收光谱，并成功辨识了胞嘧啶在0.1―3.5 THz的所有特征吸收峰。研究结果表明，这些重要的生物分子在太赫兹频段表现出鲜明的光谱特性，胞嘧啶分子3.5 THz以下的吸收特性均来源于由分子间氢键支配的外振动模式。

Terahertz Spectroscopy of DNA Nucleobases: Cytosine and Thymine

The absorption features of DNA nucleobases cytosine and thymine were measured by terahertz time-domain spectroscopy (THz-TDS) from 0.1 to 3.5 THz. Our experimental results clearly show that these important biomolecules exhibit distinctive absorption features in THz region. To the best of our knowledge, the subtle absorption peak of cytosine at 2.53 THz is reported for the first time. Moreover, geometry optimizations and lattice dynamic calculations on cytosine crystal were also performed with the pseudo-potential plane wave method of density functional theory by taking periodic boundary conditions into account. All measured terahertz absorption features of cytosine were assigned successfully and its absorption spectrum was reproduced according to our calculations. Furthermore, our results show that absorption features of cytosine below 3.5 THz arise from external modes in translation and rotation motions, which are dominated by the intermolecular hydrogen bonds.