[Study on the terahertz spectrum of Haojiami].

Haojiami is a very effective drug to treat malaria, and as a result of its unique drug efficacy, it is widely used in the clinical medicine. It was studied experimentally by terahertz (THz) time-domain spectroscopy (THz-TDS), and the characteristic absorption spectra were obtained in the range of 0.2 to 3.0 THz. In parallel with the experimental study, the density functional theory (DFT) and 6-31G basis set were applied to obtain the structure and vibrational frequencies of the haojiami molecule. The observed vibrational spectra were assigned according to the DFT calculations. Theoretical results show that 1.26 and 2.73 THz in significant agreement with experimental results at 1.24 and 2.73 THz. At the same time, haojiami's far infrared vibration pattern was recognized. The vibration mode takes the molecular groups skeleton vibration and the reverse as the chief feature. The results suggest that the use of the THz-TDS technique can be an effective way to inspect for Chinese medicine, and provide the theory basis for further study of the haojiami drug efficacy.