On the Fractal Absorption Spectra of Polymers in the Low-Frequency Part of the Terahertz Range

Abstract

The power dependence α(ν) ∝ ν^μ, where μ > 0 is the power exponent which is noninteger in the general case, is observed for amorphous polymers with a small absorption coefficient α in the low-frequency part of the terahertz range, which approximately corresponds to the frequencies ν from 0.1 to 2–3 THz. This dependence is fractal, which is due to the fractal structure of the polymer macromolecules. In this work, we find the power-law index at room temperature for the absorption coefficient of some amorphous polymers. This index is determined on the basis of the dynamics of transmission of a broadband picosecond terahertz pulse through the polymer sample, i.e., using the method of the pulse terahertz spectroscopy in the time-domain representation.