近日，日本东京大学的Eiichi Nakamura&Takayuki Nakamuro及其研究小组与以色列特拉维夫大学的Barak Hirshberg等人合作并取得一项新进展。经过不懈努力，他们对由电子束诱导的构型无序决定的晶体熔化熵进行研究。相关研究成果已于2024年5月30日在国际权威学术期刊《科学》上发表。

该研究团队通过实验发现，电子衍射信号衰减的阿列纽斯频率因子A可以通过实验方程A = A_INTW_d来提供Wd值，其中A_INT代表非弹性散射截面。

这一方法在实验层面上将克劳修斯和玻尔兹曼的理论联系起来，不仅补充了克劳修斯方法，还适用于热不稳定和生物分子晶体的毫微微克量研究。此外，数据还揭示了熔体结晶过程中的无序与结晶是互易的，两者都受到熵变的支配，但表现方向相反。

据悉，熔化后，晶体中的分子呈现出多种构型，反映出无序度的增加。无序的摩尔熵可以用玻尔兹曼公式ΔS_d = Rln(W_d)来定义，其中W_d是微观状态数的增加，目前还无法通过实验获得。

附：英文原文

Title: Melting entropy of crystals determined by electron-beam–induced configurational disordering

Author: Dongxin Liu, Jiarui Fu, Oren Elishav, Masaya Sakakibara, Kaoru Yamanouchi, Barak Hirshberg, Takayuki Nakamuro, Eiichi Nakamura

Issue&Volume: 2024-05-30

Abstract: Upon melting, the molecules in the crystal explore numerous configurations, reflecting an increase in disorder. The molar entropy of disorder can be defined by Boltzmann’s formula ΔS_d = Rln(W_d) where W_d is the increase in the number of microscopic states, so far inaccessible experimentally. We found that the Arrhenius frequency factor A of the electron diffraction signal decay provides W_d through an experimental equation A = A_INTW_d where A_INT is an inelastic scattering cross-section. The method connects Clausius and Boltzmann experimentally and supplements the Clausius approach, being applicable to a femtogram quantity of thermally unstable and biomolecular crystals. The data also showed that crystal disordering and crystallization of melt are reciprocal, both governed by the entropy change, but manifesting in opposite directions.

DOI: 10.1126/science.adk3620

Source: https://www.science.org/doi/10.1126/science.adk3620