This paper reported the theoretical and experimental vibrational spectra of β-alanine in the frequency range from 0.2 to 2.4 THz (FIR) respectively. Under the room temperature and nitrogen conditions, the absorption peak was found at 2.11 THz and the average refractive index of the pure sample was 1.96 based on the terahertz time-domain spectroscopy (THz-TDS). The absorption spectrum of β-alanine from 0.1 to 10.0 THz was simulated by PM3 algorithm of semiempiricism. The agreement between the measured and theoretical results shows the torsional vibrational modes and the structural parameters of the sample.

Key words: THz time-domain spectroscopy, β-alanine, torsional vibrational mode, quantization calculation