Dipartimento di Fisica, Universitá di Perugia , Via A. Pascoli, Perugia 06123, Italy.
J Phys Chem B. 2013 Nov 21;117(46):14477-85. doi: 10.1021/jp4054742. Epub 2013 Nov 11.
The scaling behavior of the so-called boson peak in glass-formers and its relation to the elastic properties of the system remains a source of controversy. Here the boson peak in a binary reactive mixture is measured by Raman scattering (i) on cooling the unreacted mixture well below its glass-transition temperature and (ii) after quenching to very low temperature the mixture at different times during isothermal polymerization. We find that the scaling behavior of the boson peak with the properties of the elastic medium - as measured by the Debye frequency - holds for states in which the elastic moduli follow a generalized Cauchy-like relationship, and breaks down in coincidence with the departure from this relation. A possible explanation is given in terms of the development of long-range stresses in glasses. The present study provides new insight into the boson peak behavior and is able to reconcile the apparently conflicting results presented in literature.
所谓玻色峰在玻璃形成体中的标度行为及其与系统弹性性质的关系仍然存在争议。在这里，通过拉曼散射测量了二元反应混合物中的玻色峰：(i) 在将未反应的混合物冷却到远低于其玻璃化转变温度之后，以及 (ii) 在不同时间将混合物淬火到非常低的温度之后，在等温聚合过程中。我们发现，玻色峰与弹性介质的性质（由德拜频率测量）的标度行为适用于弹性模量遵循广义 Cauchy 关系的状态，并且在偏离该关系时失效。根据玻璃中长程应力的发展给出了可能的解释。本研究为玻色峰行为提供了新的见解，并能够调和文献中呈现的明显矛盾的结果。
