Characterization of the cooling process of solid n-alkanes via terahertz spectroscopy
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The terahertz (THz) time-domain spectroscopy technique was used to characterize the cooling process of solid n-alkanes. The THz waveforms of n-octadecane, n-nonadecane, n-eicosane, n-heneicosane, n-docosane, and n-pentacosane were obtained with the cooling time using the aforementioned noncontact optical method. The peak values of the THz signal were found to be related to the cooling temperature of n-alkanes. The THz wave was sensitive to the size and structure of particles in the liquid; therefore, the crystallization process of n-alkanes was monitored. An empirical equation based on signal attenuation was proposed to quantitatively distinguish the content change of structural order in the samples. Results present a new noncontact optical approach for characterizing wax crystallization via THz time-domain spectroscopy.
Keywordssolid n-alkanes terahertz (THz) time-domain spectroscopy cooling process
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This work was supported by the National Basic Research Program of China (No. 2014CB744302), the Specially Funded Program on National Key Scientific Instruments and Equipment Development (No. 2012YQ140005), the China Petroleum and Chemical Industry Association Science and Technology Guidance Program (No. 20160107), and the National Natural Science Foundation of China (Grant No. 11574401).
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