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Proceedings Paper

How thin should a vitreous silica layer be for boson peak measurement? (Conference Presentation)
Author(s): Tsung-Chi Hung; Yu-Ru Huang; Jinn-Kong Sheu; Chi-Kuang Sun

Paper Abstract

Amorphous materials, such as glasses, polymers, gels, or even bio-tissues, are an indispensable part of our lives. Unlike crystalline solids, amorphous materials exhibit some anomalous thermal properties that are still under debate. The reduced density of vibrational states versus sound frequency near 1THz disobeys the Debye model and shows a peak, usually termed the boson peak. This excess density of states is often related to a plateau in thermal conductivity and a maximum in the reduced heat capacity around 1-10 Kelvin. This boson peak is expected to provide extra acoustic attenuation for propagating acoustic waves with a frequency around 1THz. In this presentation, we discuss the optimal thickness of a vitreous silica layer in which the THz acoustic waves will propagate through to render the acoustic attenuation constant measurement. In this potential experiment, the thickness of the vitreous silica layer becomes a critical issue. It can’t be too thick because the attenuation will be so high that the THz acoustic wave may be completely depleted; while it can’t be too thin because the wavelength (several nanometers) of the THz acoustic wave can be much longer than the layer thickness and the resulted measurement accuracy will be compromised. In this study, by using femtosecond acoustics with a bandwidth over 1THz, we explore the sample thickness issue of this much-needed experiment. Results with different layer thickness will be presented and will be compared with the current direct or indirect measurement results.

Paper Details

Date Published: 19 April 2017
PDF: 1 pages
Proc. SPIE 10102, Ultrafast Phenomena and Nanophotonics XXI, 101021K (19 April 2017); doi: 10.1117/12.2249586
Show Author Affiliations
Tsung-Chi Hung, National Taiwan Univ. (Taiwan)
Yu-Ru Huang, National Taiwan Univ. (Taiwan)
Jinn-Kong Sheu, National Cheng Kung Univ. (Taiwan)
Chi-Kuang Sun, National Taiwan Univ. (Taiwan)
Academia Sinica (Taiwan)

Published in SPIE Proceedings Vol. 10102:
Ultrafast Phenomena and Nanophotonics XXI
Markus Betz; Abdulhakem Y. Elezzabi, Editor(s)

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