Terahertz time-domain spectroscopy (THz-TDS) was used to study the asphaltenes in different crude oils. THz-TDS has a feature of measuring the amplitude and time delay and consequently the refractive index and absorption coefficient spectra simultaneously. Our approach was based on measuring the THz signal from neat crude oil samples and comparing it with the THz signal after removing the asphaltene from the oil samples (maltene). The results show that the differences in the time delay and the peak amplitude between the neat oil and the maltene have a linear relation with the asphaltene content. The refractive index spectra of the asphaltene show variation in the low THz frequencies and comparable spectra in the higher frequencies. The absorption of the asphaltene was mild, and no distinctive absorption feature was observed except for some narrow absorption peaks that we attributed to water molecules adsorbed on the asphaltene.

中文翻译：

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太赫兹光谱研究原油沥青质

太赫兹时域光谱法（THz-TDS）用于研究不同原油中的沥青质。THz-TDS具有测量振幅和时间延迟以及因此同时测量折射率和吸收系数光谱的功能。我们的方法是基于测量纯原油样品中的THz信号，并将其与从原油样品（麦芽烯）中去除沥青质后的THz信号进行比较。结果表明，纯净油和麦芽烯之间的时间延迟和峰幅度的差异与沥青质含量呈线性关系。沥青质的折射率光谱在低THz频率下显示变化，而在较高频率下可比光谱显示。沥青质的吸收很温和，