题 目：Terahertz time-domain and low-frequency Raman spectroscopy of glassy materials
报告人：Tatsuya Mori（Graduate School of Pure and Applied Sciences, Univ. of Tsukuba）
Terahertz time-domain spectroscopy (THz-TDS) enables us to detect various kinds of excitations in THz frequency region, such as superconducting gap , soft phonon , anomalous anharmonic- phonon , etc.
Glassy materials show the boson peak at THz frequency region, which is universal feature observed in specific heats, Raman spectroscopies, and inelastic neutron scattering. Far-infrared spectroscopy is also suitable to detect the boson peak spectra at THz frequency region . Here, at first, we demonstrate for vitreous SiO2 and glassy pharmaceutical indomethacin how to detect the boson peak in terms of THz-TDS, and compare the result with the phonon density of states obtained by inelastic neutron scattering, Raman spectra, and specific heat experiments. We also discuss the far-infrared coupling constant in the vicinity of the boson peak for these materials. Finally, we discuss the possibility of industrial application of the boson peak detection or imaging by THz-TDS.
 T. Mori et al., Phys. Rev. B 77, 174515 (2008). Editors’ Suggestion “Optical self-energy of superconducting Pb in the terahertz region”
 M. A. Helal, T. Mori, and S. Kojima; Appl. Phys. Lett. 106, 182904 (2015). “Softening of infrared-active mode of perovskite BaZrO3 proved by terahertz time domain spectroscopy”
 T. Mori, et al., Phys. Rev. Lett., 106, 015501 (2011). “Optical Conductivity Spectral Anomalies in the Off-center Rattling System b-Ba8Ga16Sn30”
 T. Shibata, T. Mori, and S. Kojima; Spectrochim. Acta A: Mol. Biomol. Spectrosc. 150, 207 (2015). “Low-frequency vibrational properties of crystalline and glassy indomethacin probed by terahertz time-domain spectroscopy and low-frequency Raman scattering”
Tatsuya Mori : Assistant Professor, University of Tsukuba, Japan
Ph. D from Tohoku University, Japan in 2010. 3.
Postdoctoral fellow, Institute for Molecular Science at Okazaki, Japan, 2010. 4-2011. 2
Assistant Professor, University of Tsukuba, Japan, 2011. 3 - present
Research fields: condensed matter physics (ferroelectrics, glassy materials) by means of
terahertz time-domain spectroscopy and low-frequency Raman scattering.