Study on universal excitation of glassy materials by integrated terahertz-band spectroscopy and proposal of novel evaluation method for glass

2018 Fiscal Year Final Research Report

• Project/Area Number: 17K14318
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Condensed matter physics I
• Research Institution: University of Tsukuba
• Principal Investigator: Mori Tatsuya 筑波大学, 数理物質系, 助教 (30598074)
• Project Period (FY): 2017-04-01 – 2019-03-31
• Keywords: テラヘルツ / ガラス / 高分子ガラス / ボゾンピーク / フラクタル / フラクトン

Outline of Final Research Achievements

We demonstrated that terahertz time-domain spectroscopy can detect the boson peak which is one of the unsolved problems of glass physics. In particular, by combining the terahertz spectra and vibrational density of states determined from the low-temperature specific heat, the coupling coefficients for several network glasses and molecular glasses such as glucose glass were experimentally determined and fundamental knowledge on the interaction between THz light and the vibrational density of states of glassy materials was obtained. In addition, it was shown that the fractal dynamics considered to be universal excitation of polymer glass can be detected by terahertz spectroscopy by performing the formulation of the infrared light vibrational coupling constant for fracton region.

Free Research Field

テラヘルツ分光

Academic Significance and Societal Importance of the Research Achievements

テラヘルツ時間領域分光によって、ガラスの物理の未解決問題の一つである「ボゾンピーク」を検出できることを示した。これは非晶質物質全般のテラヘルツ帯ダイナミクスを理解するための基礎知見となる。また、物質の結晶化度をボゾンピーク強度を用いて非破壊・非接触にテラヘルツ光で決定できる新たなテラヘルツ光応用方法も提案した。さらに、高分子ガラスの励起であるフラクタルダイナミクスを如何にテラヘルツ光で検出できるかについて、線形応答理論を用いて示した。これは高分子ガラスのテラヘルツスペクトルの普遍的な側面を理解するための基礎知見となる。