Fischer B M, Walther M, Uhd Jepsen P
Department of Molecular and Optical Physics, Fakultät für Physik, Albert-Ludwigs-Universität Freiburg, Stefan-Meier-Str 19, D-79104 Freiburg, Germany.
Phys Med Biol. 2002 Nov 7;47(21):3807-14. doi: 10.1088/0031-9155/47/21/319.
The far-infrared dielectric function of a wide range of organic molecules is dominated by vibrations involving a substantial fraction of the atoms forming the molecule and motion associated with intermolecular hydrogen bond vibrations. Due to their collective nature such modes are highly sensitive to the intra- and intermolecular structure and thus provide a unique fingerprint of the conformational state of the molecule and effects of its environment. We demonstrate the use of terahertz time-domain spectroscopy (THz-TDS) for recording the far-infrared (0.5-4.0 THz) dielectric function of the four nucleobases and corresponding nucleosides forming the building blocks of deoxyribose nucleic acid (DNA). We observe numerous distinct spectral features with large differences between the molecules in both frequency-dependent absorption coefficient and index of refraction. Assisted by results from density-functional calculations we interpret the origin of the observed resonances as vibrations of hydrogen bonds between the molecules.
多种有机分子的远红外介电函数由涉及构成分子的大部分原子的振动以及与分子间氢键振动相关的运动所主导。由于这些模式具有集体性质，它们对分子内和分子间结构高度敏感，因此提供了分子构象状态及其环境影响的独特指纹。我们展示了使用太赫兹时域光谱（THz - TDS）来记录构成脱氧核糖核酸（DNA）基本组成部分的四种核碱基和相应核苷的远红外（0.5 - 4.0太赫兹）介电函数。我们观察到许多不同的光谱特征，这些分子在频率依赖的吸收系数和折射率方面存在很大差异。在密度泛函计算结果的辅助下，我们将观察到的共振起源解释为分子间氢键的振动。
