Understanding the emergence of the boson peak in molecular glasses.
Understanding the emergence of the boson peak in molecular glasses.
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DOI：
10.1038/s41467-023-35878-6
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发表时间：
2023-01-13
影响因子：
16.6
通讯作者：
Wynne, Klaas
中科院分区：
文献类型：
--
作者：
Gonzalez-Jimenez, Mario;Barnard, Trent;Russell, Ben A.;Tukachev, Nikita V.;Javornik, Uros;Hayes, Laure-Anne;Farrell, Andrew J.;Guinane, Sarah;Senn, Hans M.;Smith, Andrew J.;Wilding, Martin;Mali, Gregor;Nakano, Motohiro;Miyazaki, Yuji;McMillan, Paul;Sosso, Gabriele C.;Wynne, Klaas
玻璃的一个共同特征是“玻色子峰”，在晶体上观察到的热容是过剩的，或者是太赫兹振动光谱中的一个附加峰。这一峰的微观起源还不是很清楚；局部有序结构的出现被认为是一个可能的候选。在这里，我们展示了由高度对称的分子组成的液体中的去极化拉曼散射可以用来分离玻色子峰，使其能够从液体进入玻璃进行详细的观察。振动光谱中的玻色子峰与超额热容量相匹配。当玻色子峰在冷却时增强时，广角X射线散射显示由于分子簇由大约20个分子组成，同时出现了一个预峰。原子分子动力学模拟表明，这是由配位过多的分子引起的。这些发现代表着我们朝着理解玻璃化物理迈出的重要一步。“玻色子峰”是指玻璃的太赫兹振动光谱中的一个额外峰。现在已经证明，对于高度对称的分子的液体，玻色子峰可以通过去极化的拉曼散射来挑选出来；该峰与大约20个分子的团簇的形成有关。
A common feature of glasses is the “boson peak”, observed as an excess in the heat capacity over the crystal or as an additional peak in the terahertz vibrational spectrum. The microscopic origins of this peak are not well understood; the emergence of locally ordered structures has been put forward as a possible candidate. Here, we show that depolarised Raman scattering in liquids consisting of highly symmetric molecules can be used to isolate the boson peak, allowing its detailed observation from the liquid into the glass. The boson peak in the vibrational spectrum matches the excess heat capacity. As the boson peak intensifies on cooling, wide-angle x-ray scattering shows the simultaneous appearance of a pre-peak due to molecular clusters consisting of circa 20 molecules. Atomistic molecular dynamics simulations indicate that these are caused by over-coordinated molecules. These findings represent an essential step toward our understanding of the physics of vitrification. The ‘boson peak’ refers to an extra peak in the terahertz vibrational spectrum of glasses. It is now shown that for liquids of highly symmetric molecules the boson peak can be singled out by means of depolarized Raman scattering; the peak is linked to the formation of clusters of about 20 molecules.
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DOI：
10.1039/d0cp05404f
发表时间：
2021-06-21
期刊：
Physical chemistry chemical physics : PCCP
影响因子：
--
作者：
González-Jiménez M ;Ramakrishnan G ;Tukachev NV ;Senn HM ;Wynne K
通讯作者：
Wynne K
影响因子：
8.6
作者：
Baggioli, Matteo;Zaccone, Alessio
通讯作者：
Zaccone, Alessio
影响因子：
15
作者：
BECK, JS;VARTULI, JC;SCHLENKER, JL
通讯作者：
SCHLENKER, JL
影响因子：
4.4
作者：
BUCARO, JA;LITOVITZ, TA
通讯作者：
LITOVITZ, TA
影响因子：
8.6
作者：
Huo, QS;Feng, JL;Stucky, GD
通讯作者：
Stucky, GD