Low frequency spectra of naphthalene and naphthols probed by GaP THz spectrometer
Abstract
Low frequency spectra of naphthalene, mono-, and di-hydroxy substituted naphthol isomers were obtained using GaP terahertz (THz) spectrometer. Experimental spectrum of naphthalene showed a dominant absorption band at 5.27 THz. On the other hand, quantum chemical calculations revealed an infrared active mode also at 5.27 THz which has a symmetric vibration describing a butterfly motion. Absorption spectra of naphthol isomers manifested well-defined bands above and below 5.27 THz. It is surmised that these bands have the same low frequency vibration as naphthalene and that its shift is related to the position of OH in the molecules’ structure.