Water-sensitive nature of terahertz radiation has been exploited here to discriminate the hydration states of different hydrated salts, such as Cobalt Chloride Hexahydrate (CoCl.6HO), Copper Sulfate Pentahydrate (CuSO.5HO), Magnesium Chloride Hexahydrate (MgCl.6HO), and Calcium Chloride Dihydrate (CaCl.2HO). Hydration states of these salts have been prepared by heating them in an oven at different temperature for specific time on the basis of thermo-gravimetric analysis. The prepared samples were analyzed using terahertz time-domain spectroscopy (THz-TDS). The variation in absorption coefficient and refractive indices of these hydrated salts in terahertz spectral regime (0.2–1.6 THz) are linked with the change of hydration states, which has been used for their discrimination. The results have been validated with X-ray diffraction analysis. The present work indicates that THz-TDs can be considered a promising technique to fulfill the ever increasing demand of the analysis of these hydrated salts.

中文翻译：

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使用太赫兹时域光谱判别水合盐的水合状态

这里利用太赫兹辐射的水敏感性来区分不同水合盐的水合状态，例如六水氯化钴 (CoCl.6HO)、五水硫酸铜 (CuSO.5HO)、六水氯化镁 (MgCl.6HO)、和二水氯化钙 (CaCl.2H2O)。根据热重分析，通过在不同温度的烘箱中加热特定时间来制备这些盐的水合状态。使用太赫兹时域光谱（THz-TDS）对制备的样品进行分析。这些水合盐在太赫兹光谱范围（0.2-1.6 THz）中的吸收系数和折射率的变化与水合状态的变化有关，这已被用于区分它们。结果已通过 X 射线衍射分析得到验证。目前的工作表明，太赫兹-TD 可以被认为是一种有前途的技术，可以满足这些水合盐分析不断增长的需求。