Abstract

The low-frequency vibrational spectra of two hygienic insecticides diflubenzuron and λ-cyhalothrin were investigated using terahertz time-domain spectroscopy (THz-TDS) and density functional theory (DFT) simulations. The experimental spectra of the two molecules had specific absorption peaks, which can be used as fingerprints for the molecular recognition. To understand the nature of the vibrational motions, the Gaussian03 and CRYSTAL09 were used for isolated-molecule and solid-state simulation, respectively. The solid-state DFT with CRYSTAL09 is able to reproduce high quality spectral simulations. The overall results indicate that THz-TDS technique is a potential and promising tool for pesticide discrimination and further pesticide residual detection in food and agricultural applications.

© 2012 Optical Society of America