Terahertz time-domain spectroscopic study of the low-frequency spectra of nitrobenzene in alkanes

The low-frequency spectra of nitrobenzene in alkane solvents with different chain lengths were studied by terahertz time-domain spectroscopy (THz-TDS). The peak wavenumber of the difference spectral intensity of the absorption between the solution and the solvent was shifted to a higher wavenumber with an increase in the chain length of the alkane solvents. This feature is an evidence of the presence of a characteristic frequency of the absorption in the THz region for a particular solute-solvent interacting system. We simulate our spectra using an analytical model. The amplitudes and the time constants of different processes in the low-frequency range of our study are discussed according to results of our simulation.