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）
时　间：3月10日（周四），下午2:00-3:00
地　点：南校区第一实验楼423会议室

报告摘要：

Terahertz time-domain spectroscopy (THz-TDS) enables us to detect various kinds of excitations in THz frequency region, such as superconducting gap [1], soft phonon [2], anomalous anharmonic- phonon [3], 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 [4]. 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.

[1] T. Mori et al., Phys. Rev. B 77, 174515 (2008). Editors’ Suggestion “Optical self-energy of superconducting Pb in the terahertz region”

[2] 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”

[3] T. Mori, et al.,  Phys. Rev. Lett., 106, 015501 (2011). “Optical Conductivity Spectral Anomalies in the Off-center Rattling System b-Ba₈Ga₁₆Sn₃₀”

[4] 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”

个人简介：

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.