Sasaki Toru, Oh Soo Han, Mori Tatsuya, Kojima Seiji
Department of Materials Science, University of Tsukuba, Tsukuba 305-8573, Ibaraki, Japan.
Materials (Basel). 2024 Dec 5;17(23):5956. doi: 10.3390/ma17235956.
Amber is a fragile (in Angell's classification) natural glass that has performed maturation processes over geological time. The terahertz dynamics of Baltic amber that was about 40 million years old were studied by terahertz time-domain spectroscopy (THz-TDS) in the frequency range of 0.2 and 6.0 THz. In general, the intensity of a boson peak is weak for fragile glass. In the terahertz transmission spectra of Baltic amber in the previous study, no boson peak was observed upon slow cooling. However, in the present study, upon rapid cooling down to 15 K, the boson peak was observed clearly at 0.36 THz by the suppression of ice nucleation of confined water. The dynamic correlation length determined by the boson peak frequency was compared with the static structure correlation length and the scale of the medium-range order as determined by the first sharp diffraction peak of X-ray diffraction (XRD) in the recent literature. It was found that the dynamic correlation length determined by THz-TDS was closely related to the static correlation length determined by the XRD analysis.
琥珀是一种易碎的（按照安吉尔的分类）天然玻璃，它在地质时期经历了成熟过程。利用太赫兹时域光谱（THz-TDS）在0.2至6.0太赫兹的频率范围内研究了约4000万年前的波罗的海琥珀的太赫兹动力学。一般来说，对于易碎玻璃，玻色子峰的强度较弱。在之前的研究中，波罗的海琥珀的太赫兹透射光谱在缓慢冷却时未观察到玻色子峰。然而，在本研究中，快速冷却至15K时，通过抑制受限水的冰核形成，在0.36太赫兹处清晰地观察到了玻色子峰。将由玻色子峰频率确定的动态关联长度与静态结构关联长度以及近期文献中由X射线衍射（XRD）的第一个尖锐衍射峰确定的中程有序尺度进行了比较。结果发现，由太赫兹时域光谱确定的动态关联长度与由XRD分析确定的静态关联长度密切相关。
