Terahertz Spectroscopic Study on Protein Myoglobin: Polymer-Like Behavior of Vibrational Density of States*

We performed terahertz time-domain spectroscopy on protein myoglobin to investigate the boson peak dynamics which universally appears in glassy materials and fracton which is 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 boson peak frequency. The fractal and fracton dimensions were evaluated from the obtained spectra.