It is necessary to know the terahertz dielectric constants of ice and various gas hydrates to understand their fundamental chemical and physical properties and their various possible applications. In this paper, we compare and discuss the frequency dependence and temperature dependence of the optical properties of several hydrogen-bonded solid crystals such as ice, propane hydrate and methane hydrate in the terahertz wave region. The refractive indices of ice and propane hydrate were found to be similar, while that of methane hydrate was slightly lower. The reflectivity of methane hydrate was as low as 15% that of ice, and this difference may be useful in various applications. All samples showed the same tendency with respect to the temperature dependency of their refractive indices. There was no large difference in absorption, and all samples exhibited the same frequency dependence and temperature dependence.

中文翻译：

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太赫兹应用的天然气水合物的光学参数

有必要知道冰和各种气体水合物的太赫兹介电常数，以了解其基本的化学和物理性质及其各种可能的应用。在本文中，我们比较并讨论了太赫兹波区域中几种氢键合固体晶体（如冰，丙烷水合物和甲烷水合物）的光学特性的频率依赖性和温度依赖性。发现冰和丙烷水合物的折射率相似，而甲烷水合物的折射率稍低。甲烷水合物的反射率低至冰的反射率的15％，这种差异可能在各种应用中有用。就其折射率的温度依赖性而言，所有样品均显示出相同的趋势。吸收没有太大差异，