CHEMICAL PHYSICS
·
2019
·
IF 1.822
Pengfei Wang,Liyuan Liu,Xiangchao Wang,Jianbing Zhang,Wei Qi,Hongwei Zhao,Zhen Tian,Mingxia He
A silicon-based sensor, consisting of periodical split ring resonators was demonstrated to monitor monomeric and dimeric insulin solutions in terahertz time-domain spectroscopy (THz-TDS). As concentration increases, the resonant frequencies of sensor show red shifts with a rapid trend in dilute solutions and a slow trend in concentrated solutions, consistent with CST simulations. For monomeric insulin, the turning concentration is 11.6 mg/ml and the total frequency shift is larger than that of dimeric insulin which shows a turning concentration at 17.4 mg/ml. The deviation in frequency shift and turning concentration can be attributed to the structural changes of insulin during dimerization process.
研究领域:
生物物理学
·
分析化学
✓ 已验证
产品关联
DOI
高影响因子
Journal of Spectroscopy
·
2022
·
IF 1.75
Shubao Pan,Huo Zhang,Zhi Li,Tao Chen,Xianhua Yin
This paper introduces a method to detect the content of sucrose, an adulterant of red ginseng, based on terahertz spectroscopy. Experiments were carried out on red ginseng with 6 levels of adulterated concentrations using terahertz time-domain spectroscopy (THz-TDS). We separately extracted the information of the terahertz spectral curve by principal component analysis (PCA) and Monte Carlo uninformative variable elimination (MCUVE) and then separately performed quantitative analysis by partial least squares regression (PLSR) and support vector regression (SVR). Because the nonlinear line factor in the terahertz spectral curve of red ginseng samples is considered, the MCUVE-SVR has high correlation coefficient (>0.99) and ratio prediction to deviation (>7.4), low root means square error of deviation (<1.2%), and Bias (<0.05%). The results prove that MCUVE-SVR can be regarded as an ideal quantitative analysis method in the detection of sucrose incorporation in red ginseng by terahertz spectroscopy.
研究领域:
中药学
·
光谱分析
·
食品检测
✓ 已验证
产品关联
DOI
高影响因子
Frontiers of Optoelectronics
·
2017
·Vol. 10
·期 2
·132-137
·
IF 0
Jiang Chen,Zhan Honglei,Zhao Kun,Fu Cheng
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.
研究领域:
化学
·
物理学
✓ 已验证
DOI
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
·
2020
·Vol. 22
·期 32
·17791-17797
·
IF 3.43
Ligang Chen,Guanhua Ren,Liyuan Liu,Pan Guo,Endong Wang,Zhongjie Zhu,Jinrong Yang,Jianxiong Shen,Zongchang Zhang,Lu Zhou,Jianbing Zhang,Bin Yang,Weili Zhang,Yi Gao,Hongwei Zhao,Jiaguang Han
The cooling-induced formation of a hydrate in aqueous NaCl solutions was probed using terahertz time-domain spectroscopy (THz-TDS). It was found that the NaCl hydrate formation is accompanied by the emergence of four new absorption peaks at 1.60, 2.43, 3.34 and 3.78 THz. Combining X-ray diffraction measurements with solid-state based density functional theory (DFT) calculations, we assign the observed terahertz absorption peaks to the vibrational modes of the formed NaCl·2H2O hydrate during cooling. This work shows that THz-TDS based analysis has great potential in studying ionic hydrates and the newly revealed collective vibrational modes could be sensitive indicators to achieve quantitative analysis in phase transitions and lattice dynamics.
研究领域:
物理化学
·
材料科学
✓ 已验证
DOI
高影响因子
JOM
·
2024
·
IF 2.1
Saleem Muhammad Farooq,Ashraf Ghulam Abbas,Javid Muhammad,Haleem Yasir A.,Haidry Azhar Ali,Farooq Sajid,Lei Ma,Bilal Muhammad,Habib Muhammad,Akhtar Muhammad Saeed,Khan Rashid,Wang Tianwu
Understanding the dielectric properties of materials in the THz frequency range is crucial for the advancement of THz devices. Despite their significance, the dielectric characteristics of zirconium carbide (ZrC) within this frequency range remain underexplored, in particular the impact of surface carbon and oxide layers typically found on carbide particles. While traditional studies mainly focus on particle size, this study emphasizes the pivotal role of particle morphology in determining dielectric properties. Milling was employed to increase the surface exposure of ZrC particles, which were initially covered with layers of carbon and oxides. The dielectric parameters, derived from experimental THz time-domain spectroscopy (THz-TDS) data, indicated that increased milling led to improved energy storage capabilities. This enhancement is attributed to increased electronic polarizability and charge disorder-induced ionic polarization due to the increased surface exposure. Furthermore, the dielectric properties displayed reduced dispersion after further milling attributed to the uniform particle sizes and shapes achieved through this process. Our findings underscore the critical influence of surface carbon and oxide layers on the dielectric properties of ZrC and similar carbide particles—an aspect often overlooked in studies that focus solely on particle size and shape, ignoring the distinct dielectric contributions of each surface layer.
研究领域:
材料科学
·
物理学
✓ 已验证
DOI
高影响因子
Journal of Applied Spectroscopy
·
2018
·Vol. 85
·期 1
·84-89
·
IF 0.611
Zhang J.,Xia T.,Chen Q.,Sun Q.,Deng Y.,Wang C.
The characteristic absorption spectra of paraformaldehyde and metaldehyde in the terahertz frequency region are obtained by terahertz time-domain spectroscopy (THz-TDS). In order to reduce the absorption of terahertz (THz) wave by water vapor in the air and the background noise, the measurement system was filled with dry air and the measurements were conducted at the temperature of 24°C. Meanwhile, the humidity was controlled within 10% RH. The THz frequency domain spectra of samples and their references from 0 to 2.5 THz were analyzed via Fourier transform. The refractive index and absorption coefficients of the two aldehydes were calculated by the model formulas. From 0.1 to 2.5 THz, there appear two weak absorption peaks at 1.20 and 1.66 THz in the absorption spectra of paraformaldehyde. Only one distinct absorption peak emerges at 1.83 THz for metaldehyde. There are significant differences between the terahertz absorption coefficients of paraformaldehyde and metaldehyde, which can be used as "fingerprints" to identify these substances. Furthermore, the relationship between the average absorption coefficients and mass concentrations was investigated and the average absorption coefficient–mass concentration diagrams of paraformaldehyde and metaldehyde were shown. For paraformaldehyde, there is a linear relationship between the average absorption coefficient and the natural logarithm of mass concentration. For metaldehyde, there exists a simpler linear relationship between the average absorption coefficient and the mass concentration. Because of the characteristics of THz absorption of paraformaldehyde and metaldehyde, the THz-TDS can be applied to the qualitative and quantitative detection of the two aldehydes to reduce the unpredictable hazards due to these substances.
研究领域:
化学
·
光谱学
✓ 已验证
产品关联
DOI
高影响因子
INFRARED PHYSICS & TECHNOLOGY
·
2024
·
IF 3.1
Tong Zhang,Zhiyuan Zheng,Mingrui Zhang,Shanshan Li,Xiaodi Zheng,Haochong Huang,Junfeng Shen,Zili Zhang,Kunfeng Qiu
The Bayan Obo deposit is the world’s largest polymetallic associated minerals deposit of rare earths, iron and niobium, and the rarity of its physical properties restrict the knowledge and understanding of its laws. Taking the high-grade mixed rare earth concentrate of Bayan Obo as the research object, terahertz time-domain spectroscopy (THz-TDS) has been adopted for the systematic investigation of high-grade rare earth concentrate base on the traditional X-ray fluorescence (XRF), X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetric-differential thermal analysis (TG-DTA). The absorption coefficient and refractive index of high-grade rare earth ores and their associated minerals of fluorite and dolomite, are all investigated by terahertz time-domain spectroscopy. The terahertz spectral response is affected by the type of mineral and its content. The acquired rare earth terahertz spectral data are processed by correlation analysis. Three machine learning algorithms, Partial Least Squares Regression (PLSR), Random forest (RF) and Multilayer Perceptron (MLP), are used to achieve quantitative detection of their concentrations and components with the coefficient of determination R 2 of the absorption coefficient of the optical parameter reaching up to 0.975, 0.992 and 0.984, respectively. This work promotes the growing understanding of terahertz transmission spectroscopy of rare earth-bearing minerals, which can be used to help guide the search for minerals, and to detect, identify as well as quantify them in geology. Terahertz time-domain spectroscopy supplies a new method for study of rare earth resources, and the comprehensive development and utilization of resources in the Bayan Obo deposit.
研究领域:
矿物学
·
光谱学
·
地质学
✓ 已验证
DOI
高影响因子
OPTICS EXPRESS
·
2025
·Vol. 33
·期 4
·6918-6927
·
IF 3.3
Yan Qiu,Lirong Gong,Haobo Zhai,Long Hu,Bowen Lu,Yuhua Hang,Yongdong Li
We investigate the physical mechanisms of the interaction between terahertz waves and antioxidant 1010 in polyethylene (PE) using terahertz time-domain spectroscopy (THz-TDS). The THz waves are generated by an InGaAs photoconductive emitter antenna and detected by an InGaAs photoconductive receiver antenna, which are both driven by a pulsed laser with a wavelength of 1560 nm, pulse repetition rate of 80 MHz, and pulse duration of 100 fs. With increasing concentrations of antioxidants, the absorption spectrum exhibits a marked increase in the intensity of the absorption peaks at 0.91, 1.20, 1.52, and 1.71 THz and a corresponding reduction in their broadening. The absorption spectrum calculated from the density functional theory-based numerical model developed in this work aligns with the experimental data, confirming the fact that THz absorption strengthens the van der Waals interactions between molecular groups, with methyl groups exhibiting stronger interactions than oxygen-containing groups, which drives collective multiatomic vibrations. The frequency-resolved calibration curve for the antioxidant concentration is optimal at 0.77 THz (coefficient of determination R2 = 0.99476, root-mean-square error of cross-validation RMSECV = 2.67 wt.%) rather than at the absorption peak frequencies, stemming from the combined effects broadband absorption peaks. These findings provide the THz spectral response of antioxidant molecules in PE both theoretically and experimentally, and they demonstrate the potential of THz-TDS as a rapid, accurate, and non-destructive method for quantifying antioxidant concentration in polymer cables for power systems.
研究领域:
材料科学
·
光谱学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
OPTIK
·
2018
·
IF 1.191
Haishun Liu,Zhenwei Zhang,Yuping Yang,Tao Chen,Cunlin Zhang
Terahertz time-domain spectroscopy (THz-TDS) was employed to measure the absorption spectra for three types of dyestuff at the frequency range of 0.3–2.2 THz. The raw spectra data were implemented dimensionality reduction by using principal component analysis (PCA). Depending on the weak cluster trend determined by the score plot, different levels of Savitzky-Golay (SG) smoothing combined with PCA processing was performed for elevating the recognition rate. The recognition effects were assessed by fuzzy c-means (FCM) and k-means clustering techniques, which consistently demonstrated the combination of polynomial order 1 and window size 5 for SG smoothing achieved the highest accuracy of 94.44%. For k-means and FCM clustering, the identification accuracies of raw spectra were 87.5% and 84.72% respectively, suggesting the elevation recognition rate by using SG smoothing with polynomial order 1 and window size 5. Our results suggested SG smoothing coupled with PCA was a potent method to cope with THz spectra recognition for dyestuffs.
研究领域:
化学
·
光谱学
✓ 已验证
DOI
高影响因子
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
·
2022
·Vol. 24
·期 38
·23490-23496
·
IF 3.945
Yuyue Yan,Jiaqi Zhang,Guanhua Ren,Lu Zhou,Liyuan Liu,Xueqian Zhang,Ligang Chen,Chunmei Ouyang,Jiaguang Han
The interaction of MgCl2 with H2O is heavily involved in biological and chemical processes. In this work, freezing-induced hydrate formation from MgCl2 aqueous solution was monitored using terahertz time-domain spectroscopy. At low temperatures, two phase transitions from brine to hydrate formation could be clearly observed, and the formation of hydrate was accompanied by the emergence of new THz fingerprint peaks at 1.02, 1.56, and 1.84 THz, respectively. Integrating XRD and quantum chemical calculations, we attributed the absorption peaks to the vibrational modes of the formed MgCl2·12H2O. This demonstrates the potential of THz spectroscopy for application in the detection of biological processes in low-temperature environments, such as cell freezing.
研究领域:
化学
·
生物物理学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF MOLECULAR STRUCTURE
·
2021
·
IF 3.196
Yujing Bian,Xun Zhang,Zhenqi Zhu,Bin Yang
To date, it is challengeable to clearly identify and accurately characterize molecular vibrational modes of an amino acid and its hydrate. In this work, the terahertz absorption spectra of L -Lysine (Lys) and L -Lysine hydrate (Lys·H 2 O) have been measured by terahertz time-domain spectroscopy (THz-TDS) at the range of 0.3–2.5 THz under room temperature. The structural changes of Lys and Lys·H 2 O are sensitively observed by THz spectroscopy. Based on density functional theory (DFT), the vibrational frequencies of Lys and Lys·H 2 O are analyzed, the Lys single molecule model and the most optimal Lys·H 2 O single molecule model are established. The collective vibrational modes of Lys and Lys·H 2 O have been identified by potential energy distribution (PED) analysis and molecular vibrational animation of GaussView. The results demonstrate that the collective vibrational modes of Lys and Lys·H 2 O at various frequencies are originated from the dihedral torsion or the bond angle bend of different molecular chains in a single molecule, which drives the vibrations of related groups. Therefore, the combination of THz-TDS technology and PED analysis opens up an opportunity for identifying Lys and its hydrate, which provides a theoretical reference for studying vibrational modes of biomolecules.
研究领域:
生物物理学
·
光谱学
·
理论化学
✓ 已验证
DOI
高影响因子
APPLIED OPTICS
·
2017
·Vol. 56
·期 20
·5698-5704
·
IF 1.65
Y. Huang,P. Sun,Z. Zhang,C. Jin
Water vapor noise in the air affects the accuracy of optical parameters extracted from terahertz (THz) time-domain spectroscopy. In this paper, a numerical method was proposed to eliminate water vapor noise from the THz spectra. According to the Van Vleck–Weisskopf function and the linear absorption spectrum of water molecules in the HITRAN database, we simulated the water vapor absorption spectrum and real refractive index spectrum with a particular line width. The continuum effect of water vapor molecules was also considered. Theoretical transfer function of a different humidity was constructed through the theoretical calculation of the water vapor absorption coefficient and the real refractive index. The THz signal of the Lacidipine sample containing water vapor background noise in the continuous frequency domain of 0.5–1.8 THz was denoised by use of the method. The results show that the optical parameters extracted from the denoised signal are closer to the optical parameters in the dry nitrogen environment.
研究领域:
物理学
·
光谱学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）