Department of Physics and Astronomy, University of California, Riverside, Riverside, California 92521, USA.
J Chem Phys. 2010 Jun 28;132(24):245102. doi: 10.1063/1.3457941.
We use terahertz time domain spectroscopy (THz-TDS) to determine the complex frequency-dependent dielectric response of all four nucleotides at different dilute concentrations. In addition, the suspension model's ability to extract the dielectric response of just the nucleotide with the hydration shell epsilon(b) excluding the dielectric information relating to the bulk will be verified. The suspension model enables us to make the determination that the nucleotides have influences on the water molecules out to the fourth hydration shell. We use a two Debye relaxation fit model for water, all concentrations and all epsilon(b) values. We observed how the nucleotides affect the relaxation parameters in relation to that of pure bulk water. With this information, we notice a transition between purines and pyrimidines, where one is a hydrogen-bond network structure building type material with a low concentration increment and the other is a structure breaking type material with a low concentration decrement. Due to conductivity measurements, we determine that kinetic depolarization is a negligible affect compared to that of dielectric saturation, which we find to dominate where a decrement is found.
我们使用太赫兹时域光谱（THz-TDS）来确定所有四种核苷酸在不同稀释浓度下的复频相关介电响应。此外，还将验证悬浮模型是否能够提取仅具有水化壳ε（b）的核苷酸的介电响应，而排除与体相相关的介电信息。悬浮模型使我们能够确定核苷酸对水分子的影响一直延伸到第四水化壳。我们使用两个德拜弛豫拟合模型来表示水，包括所有浓度和所有ε（b）值。我们观察了核苷酸如何影响弛豫参数，以及与纯体相水的关系。有了这些信息，我们注意到嘌呤和嘧啶之间的转变，其中一种是氢键网络结构构建型材料，浓度增量较低，另一种是结构破坏型材料，浓度减量较低。由于电导率测量，我们确定与介电饱和相比，动力学去极化的影响可以忽略不计，而我们发现介电饱和在出现减量时占主导地位。
