Te Ji

Far-infrared characteristics of NaCl and alkali halide

The optical and dielectric properties of NaCl and alkali halide are studied by Terahertz time-domain spectroscopy (THz-TDS) technique from 0.3 THz to 1.4 THz. The absorption spectral features of measured samples are discussed based on their characteristic and common features. Further, the measured complex refractive index and dielectric functions of NaCl are well fitted by a standard Lorentz model. Theoretical calculations indicate that characteristic phonon resonance of NaCl is dominated by the transverse optical phonon mode at 5.10 THz.

Terahertz time-domain spectroscopy study of solid state reaction between α-naphthol and p-benzoquinone

Terahertz time-domain spectroscopy (THz-TDS) was utilized to study solid state reaction progress between α-naphthol(NP) and p-benzoquinone(BQ). Density functional theory (DFT) was employed to optimize the structure of the complex. The result shows that the reaction product is associated by hydrogen bonding between one of the oxygen atoms of BQ and one hydrogen atom of the hydroxyl group of NP; and FTIR spectra is presented as supporting evidence. Our work demonstrated that THz-TDS was a promising and complementary method in analyzing solid-state reaction between NP and BQ.

The THz fingerprint spectra of the active ingredients of a TCM medicine: Herba Ephedrae

In this paper, THz-TDS has been used to measure the spectral properties of two active ingredients of Herba Ephedrae: ephedrine and pseudoephedrine, which exist in hydrochloride salts. The THz spectra of the sole-ingredient, twoingredient and three-ingredient compounds are studied. We obtained the finger-print spectra of the net active ingredients of the medicine, and also measured the mixtures of by two or three active ingredients at the different ratios. At the same time, theoretical analysis and quantitative analysis is applied to foretell the different THz spectra, identify the ingredients and infer the contents of principal components in samples. The THz spectroscopy is a potential and promising technique in evaluating and inspecting the quality of the drugs in the TCM field.