Boson Peak and Fracton of Polymethyl Methacrylate Detected by Terahertz-band Infrared and Raman Spectroscopies

We performed terahertz time-domain spectroscopy and low-frequency Raman scattering on polymethyl methacrylate to investigate the boson peak (BP) which is a universal excitation in glass, and the fracton which is expected to be expressed in polymer glass. In the infrared spectrum, the BP was observed in the plot of alpha(nu)/nu(2), where alpha(nu) is the absorption coefficient. In addition, the infrared light-vibration coupling constant C-IR(nu) and the Raman coupling constant C-Raman(nu) were determined, and the fracton was observed as a linear region in the log-log plots of C-IR(nu) and C-Raman(nu).

Automated summary

The study found the existence of boson peak and fracton in polymethyl methacrylate, with the determination of infrared light-vibration coupling constant and Raman coupling constant. The fracton was observed as a linear region in log-log plots of the coupling constants.