Spectroscopy studies on the selected nitropolycyclic aromatic hydrocarbons compounds in the terahertz region

Abstract

In this work, vibrational properties of a series of parent polycyclic aromatic hydrocarbons (PAHs) and nitropolycyclic aromatic hydrocarbons (NPAHs) compounds with the substituted nitro group at different positions have been investigated using terahertz time-domain spectroscopy (THz-TDS) at room temperature. The experimental results show large difference among absorption spectra of several NPAHs and their corresponding parent PAHs compounds in 0.1~2.2 THz region, which probably originated from the difference of NPAHs' molecular structure and lattice vibrational modes. All the experimental NPAHs vibrational modes showed distinct fingerprint absorption in THz region. The study indicates that THz-TDS technology can not only give a new experimental method to identify and analyse such different kinds of NPAHs environmental pollutants, but also provide a useful suggestion for further assessing the possible relationships between the NPAHs optical properties and the effects of the substituted nitro group position to better know their photoreactivity and biochemical activities.