Abstract-Far-infrared terahertz properties of L-cysteine and its hydrochloride monohydrate

Guanhua Ren, Siqi Zong, Zhongjie Zhu, Chao Cheng. Ligang Chen,  Lu. Zhou, Jianbing Zhang, Liyuan Liu, Jiaguang Han, Hongwei Zhao

https://www.sciencedirect.com/science/article/pii/S1386142519308662

As the building blocks of proteins, amino acids serve vital metabolic functions in addition to protein synthesis and thus attract enormous interest. Here we reported the far-infrared optical properties of L-cysteine (Lcys) and its hydrochloride monohydrate (LCHM) characterized by terahertz time-domain spectroscopy. The Lcys and LCHM exhibit quite distinct characteristics in the terahertz region due to diverse collective vibrations of the molecules, which is further confirmed by the solid-state density functional theory (DFT) calculations. The presented studies indicate that the intermolecular hydrogen bonds play a critical role in the far-infrared terahertz response of Lcys and LCHM.

Abstract-Label-Free Measurements on the Solution of Monomeric and Dimeric Insulin Using a Periodical Terahertz Split Ring Resonator

Pengfei Wang, Liyuan Liu,  Xiangchao Wang, Jianbing Zhang, Wei Qi, Hongwei Zhao, Zhen Tian, Mingxia He



https://www.sciencedirect.com/science/article/abs/pii/S0301010419300035

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 11.6mg/ml and the total frequency shift is larger than that of dimeric insulin which shows a turning concentration at 17.4mg/ml. The deviation in frequency shift and turning concentration can be attributed to the structural changes of insulin during dimerization process.

Abstract-Self-Assembled Chiral Nanoribbons Studied by Terahertz Time-Domain Spectroscopy and Other Biological Methods

Pengfei Wang, Yuefei Wang, Liyuan Liu, Jinwu Zhao, Zhen Tian, Wei Qi, Jianbing Zhang, Hongwei Zhao, Mingxia He



https://www.sciencedirect.com/science/article/abs/pii/S0009261419300363

We report the use of terahertz time-domain spectroscopy (THz-TDS) to probe chiral self-assembled twisted nanoribbons from a ferrocene-modified dipeptide consisting of two L-amino acids (Fc-FF). Supported by molecular dynamics simulation, the THz absorption peaks at 0.9 THz and 2.7 THz are attributed to distinct characteristic vibrational modes of Fc-FF single crystal. The relative absorption intensity is introduced to characterize the discrepancy in THz peak absorption which originates from symmetry breaking. Combined with the results of scanning electron microscopy, circular dichroism, Fourier transform infrared spectroscopy and X-ray diffraction, THz-TDS unravels great potentials to distinguish subtle structural changes within chiral self-assembled materials.

Abstract-Anisotropic plasmonic response of black phosphorus nanostrips in terahertz metamaterials

Qingqing Fo,  Ling Pan, Xieyu Chen, Quan Xu, Chunmei Ouyang, Xueqian Zhang,   Zhen Tian, Jianqiang Gu, Liyuan Liu,   Jiaguang Han,  Weili Zhang

https://ieeexplore.ieee.org/document/8369157/

Two-dimensional black phosphorus (BP) recently emerged as an outstanding material for optoelectronics and nanophotonics applications. In contrast to graphene, BP has a sufficiently large electronic bandgap and its high carrier mobility allows for efficient free-carrier absorption in the infrared and terahertz regimes. Here, we present a reflective structure to enhance the response of nanostructured monolayer BP at terahertz frequencies and investigate localized surface plasmon resonances in BP nanostrip arrays. Anisotropic absorption is observed in the proposed BP metamaterials due to the puckered crystal structure of monolayer BP, and further investigations show that the plasmonic resonances are strongly depending on the geometric parameters of the nanostrips and the coupling between the adjacent nanostrips. We expect that the monolayer BP is an outstanding candidate of highly anisotropic plasmonic material for ultra-scaled optoelectronic integration.