Resonant absorption mechanism for THz frequency ultrasonic and electromagnetic waves in glasses

A resonant mechanism is suggested for absorption of ultrasonic and electromagnetic waves of THz frequencies in glasses exhibiting both the boson peak and high frequency sound. The absorption is due to resonant transitions for single harmonic soft-mode related excitations determining the THz frequency dynamics of such glasses. The frequency dependence of the absorption coefficient is found to exhibit a broad peak similar to the boson peak in scattering spectra. It is argued that, under appropriate conditions, the predicted qualitative behavior of the absorption coefficient can be observed in experiment