Pogna E A A, Chumakov A I, Ferrante C, Ramos M A, Scopigno T
Laboratorio NEST , CNR-INFM and Scuola Normale Superiore , Piazza San Silvestro 12 , I-56127 Pisa , Italy.
Dipartimento di Fisica , Politecnico di Milano , Piazza Leonardo da Vinci 32 , I-20133 Milano , Italy.
J Phys Chem Lett. 2019 Feb 7;10(3):427-432. doi: 10.1021/acs.jpclett.9b00003. Epub 2019 Jan 15.
Fossil amber offers the unique opportunity to investigate an amorphous material that has been exploring its energy landscape for more than 110 million years of natural aging. By applying different X-ray scattering methods to amber before and after annealing the sample to erase its thermal history, we identify a link between the potential energy landscape and the structural and vibrational properties of glasses. We find that hyperaging induces a depletion of the vibrational density of states in the terahertz region, also ruling the sound dispersion and attenuation properties of the corresponding acoustic waves. Critically, this is accompanied by a densification with structural implications different in nature from that caused by hydrostatic compression. Our results, rationalized within the framework of fluctuating elasticity theory, reveal how upon approaching the bottom of the potential energy landscape (9% decrease in the fictive temperature) the elastic matrix becomes increasingly less disordered (6%) and longer-range correlated (22%).
化石琥珀提供了一个独特的机会，来研究一种非晶材料，这种材料在超过1.1亿年的自然老化过程中一直在探索其能量景观。通过在对样品进行退火以消除其热历史之前和之后，对琥珀应用不同的X射线散射方法，我们确定了势能景观与玻璃的结构和振动特性之间的联系。我们发现，超老化会导致太赫兹区域的振动态密度耗尽，这也决定了相应声波的声色散和衰减特性。至关重要的是，这伴随着致密化，其结构影响在本质上与静水压缩引起的不同。我们的结果在波动弹性理论的框架内得到了合理的解释，揭示了在接近势能景观底部时（虚构温度降低9%），弹性基体如何变得越来越无序（6%）且长程相关性越来越强（22%）。
