Investigation on Characteristics of Edible Oil Spectra with Terahertz Time-Domain Attenuated Total Reflection Spectroscopy
NIE Mei-tong1，2, XU De-gang1，2*, WANG Yu-ye1，2*, TANG Long-huang1，2, HE Yi-xin1，2, LIU Hong-xiang1，2, YAO Jian-quan1，2
1. Institute of Laser and Optoelectronics, School of Precision Instrument and Optoelectronics Engneering, Tianjin University, Tianjin 300072, China
2. Key Laboratory of Optoelectronic Information Science and Technology (Ministry of Education), Tianjin University, Tianjin 300072, China
Abstract：Edible oil is a significant source of human nutrition and energy, providing essential fatty acids for human body. Thus, the investigation on the optical properties of edible oils in THz region for component analysis and quality evaluation is considered to be of great importance. As a newly developed-technique, Terahertz time-domain attenuated total reflection spectroscopy can obtain the THz spectra through the interaction between sample and evanescent wave. Compared with Terahertz time-domain transmission or reflection spectroscopy, this technique can effectively avoid the influence of sample cell when measuring liquid samples such as edible oils, thus acquiring the optical parameters more accurately. The absorption spectra of soybean oil were measured via both Terahertz time-domain transmission spectroscopy and Terahertz time-domain attenuated total reflection spectroscopy. Compared with Terahertz time-domain transmission spectroscopy, the Terahertz time-domain attenuated total reflection spectroscopy showed greater advantages in acquiring the absorption coefficients and distribution of absorption peaks. Furthermore, the optical properties of soybean oil, walnut oil and grape seed oil were investigated by using Terahertz time-domain attenuated total reflection spectroscopy. In addition, the refractive index and absorption spectra of the three edible oils in the range from 1 to 1.8 THz were obtained. Using density functional theory, we also calculated the vibration and rotation modes of four kinds of principal components (hexadecanoic acid, octadecanoic acid, octadecenoic acid, and octadecadienoic acid) in THz region which were consistent well with the experimental results. In conclusion, the absorption peaks of edible oils in terahertz region are related to the components and contents of fatty acidsas well as result from their vibration and rotation modes. Moreover, this research may contribute to qualitative and quantitative components analysis as well as quality inspection of edible oils.
Key words：Terahertz spectra; Edible oil; Density functional theory
聂美彤，徐德刚，王与烨，唐隆煌，贺奕焮，刘宏翔，姚建铨. 基于衰减全反射式太赫兹时域光谱技术的食用油光谱特性研究[J]. 光谱学与光谱分析, 2018, 38(07): 2016-2020.
NIE Mei-tong, XU De-gang, WANG Yu-ye, TANG Long-huang, HE Yi-xin, LIU Hong-xiang, YAO Jian-quan. Investigation on Characteristics of Edible Oil Spectra with Terahertz Time-Domain Attenuated Total Reflection Spectroscopy. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2018, 38(07): 2016-2020.
[1] Ferguson B, Zhang X C. Nature Materials, 2002, 1(1): 26.
[2] Baxter J B, Schmuttenmaer C A. Journal of Physical Chemistry B, 2006, 110(50): 25229.
[3] Tonouchi M. Nature Photonics, 2007, 1(2): 97.
[4] Kleine-Ostmann T, Nagatsuma T. Journal of Infrared, Millimeter, and Terahertz Waves, 2011, 32(2): 143.
[5] LI Jiu-sheng, LI Xiang-jun(李九生，李向军). Acta Physica Sinica(物理学报), 2009, 58(8): 5805.
[6] Li J S. IEEE Transactions on Instrumentation and Measurement, 2010, 59(8): 2094.
[7] Yin M, Tang S, Tong M. Analytical Methods, 2016, 8(13): 2794.
[8] Hirori H, Yamashita K, Nagai M, et al. Japanese Journal of Applied Physics, 2004, 43(10A): L1287.
[9] Arikawa T, Nagai M, Tanaka K. Chemical Physics Letters, 2009, 477(1): 95.
[10] Shiraga K, Ogawa Y, Suzuki T, et al. Applied Physics Letters, 2013, 102(5): 053702.
[11] Choi D H, Son H, Jeong J Y, et al. Chemical Physics Letters, 2016, 659(1): 164.
[12] MA Chun-qian, XU Xiang-dong, ZOU Rui-jiao, et al(马春前，许向东，邹蕊矫，等). Spectroscopy and Spectral Analysis(光谱学与光谱分析), 2015, 35(4): 870.
[13] Taday P F. Philosophical Transactions of the Royal Society A, 2004, 362(1): 351.
