Fig. 1. Schematic of terahertz time－domain spectroscopy system

Fig. 2. Experimental and simulated absorption spectra of ANPZ (the dash lines represent each single simulated absorption)

Fig. 3. Crystal cell of ANPZ (the red, blue, grey and white balls represent the O, N, C and H atoms, respectively)

Fig. 4. Hydrogen bonding networks of ANPZ(the dash lines represent the hydrogen bonds)

Fig. 5. Vibrational modes at 1.14 THz and 1.92 THz (the green arrows describe the displacement vectors of each atom)

Fig. 6. THz spectra of ANPZ from 24 ℃ to 150 ℃