Terahertz and Far-infrared Absorption Spectroscopic Study of DNA Bases

It is important to know the higher-order structure of deoxyribonucleic acid (DNA) since DNA has been considered to be a candidate for an emerging dielectric material. Regarding this, terahertz (THz) and far-infrared (FIR) absorption spectra were measured for guanine, a constituent base of DNA. In addition, quantum chemical calculations using density function theory were conducted for three types of guanine models to simulate the acquired absorption spectra. As a result, it is clarified that the absorption peaks appearing in the FIR and THz ranges are assigned to skeletal or intermolecular vibrations.