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Seminar Announcement: Tatsuya Mori

posted Dec 7, 2017, 12:00 AM by Stefano Varas   [ updated Dec 21, 2017, 1:19 AM ]

Wednesday, 6 December 2017, 15:00
Sala Grande Palazzina B via alla Cascata 56/C

"Boson peak investigation of glassy materials by terahertz time-domain spectroscopy"

Tatsuya Mori
Division of Materials Science Faculty of Pure and Applied Sciences
University of Tsukuba, 1-1-1 Tennoudai, Tsukuba, Ibaraki 305-8573, Japan

The boson peak (BP) has been one of the unsolved problems on glass physics, and it appears in the THz region as a universal excitation. The BP is famously detected by inelastic neutron or X-ray scattering, low-frequency Raman scattering, and low-temperature specific heat measurements. On the other hand, there have been few experimental investigations by far-infrared spectroscopy, although the technique is complemental method of Raman spectroscopy.
Recently, we showed that THz time-domain spectroscopy is suitable technique for the detection of the BP [M. Kabeya, T.M. et al., Phys. Rev. B 2016]. One of the advantages of the THz spectroscopy is the ability to determine the absolute value of the infrared light-vibration coupling coefficient (CIR).
In this lecture, we evaluate the CIR of the glassy glucose using Taraskin’s universal model [S. N. Taraskin et al., Phys. Rev. Lett. 2006]. We will see that the large absorption in the vicinity of the BP of the glassy glucose is caused by both the “light mass” effect and the disordered charge distribution.

Stefano Varas,
Dec 7, 2017, 12:00 AM