Study on THz spectrum of artemeter

Artemeters are studied by Terahertz time-domain spectroscopy, and the characteristic absorption spectra are obtained in the range of 0.2-3.0 THz. The vibration frequencies are calculated with the density functional theory (DFT). Theoretical results in1.26 and 2.73 THz are agreement with the experimental results in 1.24 and 2.73 THz, and identification of vibration modes is also given. Our results show that the normal modes at low frequencies not only correspond to the inter- and intra-molecular vibrations but also the coupling between inter- and intra-molecular motions.