Far-infrared absorption spectra by THz radiation: its application to biopolymers

Summary form only given. There has been dramatic progress in generation and detection of freely propagating terahertz (THz) radiation in the late 1990s. THz radiation has been successfully applied to far infrared (FIR) absorption spectroscopy in the field of molecular science. Recently significance of low-frequency modes in biopolymers has been theoretically emphasized through the relation between these modes and functionality of biomolecules. We focused on characteristics of low-frequency modes intrinsic to biopolymers and measured FIR absorption spectra of a protein (cytochrome c) in different conformations and polypeptides (polyglycine and polyalanine) with THz radiation as a light source.