Terahertz time domain spectroscopy of complex dielectric constants of boson peaks

Abstract

Using THz time domain spectroscopy we have observed both the real and the imaginary parts of complex dielectric constants in the far-infrared region for a glassy polymethyl methacrylate (PMMA). The intensity and phase of transmittance of PMMA were accurately measured in the frequency range between 5 and 110 cm-1. The strong absorption appeared around a boson peak (BP) frequency, which was also observed by Raman scattering. The broad peak of an imaginary part related to BP shows a similar line-shape to the reduced depolarized Raman spectrum. © 2003 Elsevier Science B.V. All rights reserved.