Terahertz spectroscopy investigation of preservative molecules

We obtained the terahertz (THz) absorption characteristics of six types of preservatives in the 0.2–2 THz range using THz time-domain spectroscopy (THz-TDS). The structural and vibrational frequencies of the samples were calculated using density functional theory (DFT); the calculated results fit well with the experimental data. Assignments of the observed THz absorptions were proposed, based on the DFT calculations. The results indicate that the measured characteristic frequencies arise from the collective vibration of intramolecular, intermolecular, and phonon modes. This work demonstrates that THz-TDS spectroscopy can be useful for investigating preservatives in food and agriculture products.