Research on the Terahertz Absorption Spectra of Histidine Enantiomer (L) and its Racemic Compound (DL).
Terahertz time-domain spectroscopy (THz-TDS) is used to investigate the absorption spectra of polycrystalline L- and DL-histidine in the frequency range of 10-100 cm-1. The spectra exhibit distinct differences in peak frequencies between the enantiomer (L-histidine) and racemic compound (DL-histidine). The observed spectral differences are attributed to the intermolecular interactions. With the density function theory (DFT) method, the frequencies of vibrational modes of L-histidine and DL-histidine in the THz range are calculated and well assigned according to the measured spectra. The origin of the observed vibrational modes is found to be non-localized and of a collective (phonon-like) nature, which points to the lattice and skeleton vibrations mediated by the hydrogen bond. Furthermore, we propose and demonstrate a method for determining the composition ratio of histidine mixtures based on the THz absorption spectra.
1 Key Laboratory of Terahertz Solid-State Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Science, Shanghai, China.
Tao
T
Zhou
1 Key Laboratory of Terahertz Solid-State Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Science, Shanghai, China.
Yidong
Y
Wu
1 Key Laboratory of Terahertz Solid-State Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Science, Shanghai, China.
Juncheng
J
Cao
2 Shanghai Advanced Research Institute, Shanghai, China.
Liangliang
L
Zou
3 Department of Radiology, Hua shan Hospital, Fu dan University, Shanghai, China.
Jie
J
Yuan
3 Department of Radiology, Hua shan Hospital, Fu dan University, Shanghai, China.
Zhenwei
Z
Yao
4 Engineering Research Center of Optical Instrument and System, Ministry of Education and Shanghai Key Lab of Modern Optical System, University of Shanghai for Science and Technology, Shanghai, China.
Gongjie
G
Xu
Absorption spectrum; collective vibration; composition identification; histidine; terahertz