Terahertz Time-Domain Spectroscopy of Protein Myoglobin: Detection of Boson Peak and Fracton

We performed terahertz time-domain spectroscopy on protein myoglobin to detect the universal boson peak (BP) behavior in glassy materials and fracton expected to universally appear in polymer glasses. The obtained spectral shape of log ε” vs log frequency [ε”: the imaginary part of complex dielectric constants] indicates that the fracton region appears above the BP frequency. The fractal and fracton dimensions were evaluated from the obtained spectra.