Terahertz Time-Domain Spectroscopic Study of Boson Peak of Hydrogen-Bonded Glass-Forming Glycerol

The universal excitation of glass, the boson peak (BP), was detected by terahertz time-domain spectroscopy in glassy glycerol, and the interaction between the BP and terahertz light was investigated. The BP frequency of the observed infrared spectra is approximately 1.4 times higher than that of the vibrational density of states spectra. Furthermore, the difference causes a linear behavior in the infrared light-vibrational coupling coefficient (C-IR(v)) in the vicinity of the BP frequency. This behavior deviates from the C-IR(v) = A + Bv(2) predicted by Taraskin's model [Phys. Rev. Lett. 97, 055504 (2006)] and implies the need to modify the model.