We report the optical constants of the solid CO₂ (dry ice) measured using terahertz time domain spectroscopy. The CO₂ ice sample was grown by vapor deposition method. The optical constants were obtained by minimizing the amplitude of the oscillations of refractive index in the spectral domain. We found that the mean refractive index of CO₂ ice at 10 K is 1.485 between 0.2 and 1.6 THz with a standard deviation of 0.0137. The experiments were accompanied by first-principles density functional theory calculations using full-potential linear augmented plane wave method. The calculated refractive index is found to be 1.37 which is in reasonable agreement with the experimental value. In addition, the vibrational frequencies of solid CO₂ were also studied using density functional perturbation theory, and the corresponding modes were assigned.

中文翻译：

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固体CO 2的太赫兹光学常数

我们报告使用太赫兹时域光谱仪测量的固体CO ₂（干冰）的光学常数。通过气相沉积法使CO ₂冰样品生长。通过使光谱域中的折射率振荡的幅度最小来获得光学常数。我们发现，CO ₂冰在10 K下的平均折射率在0.2和1.6 THz之间为1.485，标准偏差为0.0137。实验伴随着使用全电位线性增强平面波方法进行的第一性原理密度泛函理论计算。发现计算出的折射率为1.37，与实验值合理地吻合。另外，固体CO ₂的振动频率 还使用密度泛函微扰理论对它们进行了研究，并指定了相应的模式。