Photon Activation of Glassy Dynamics: A Mechanism for Photoinduced Fluidization, Aging, and Information Storage in Amorphous Materials
Photon Activation of Glassy Dynamics: A Mechanism for Photoinduced Fluidization, Aging, and Information Storage in Amorphous Materials
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DOI：
10.1021/acs.jpcb.0c06515
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发表时间：
2020-09-24
影响因子：
3.3
通讯作者：
Wolynes, Peter G.
中科院分区：
文献类型：
--
作者：
Lubchenko, Vassiliy;Wolynes, Peter G.
我们讨论了光子激活的玻璃熔体和冷冻玻璃中的分子，可以光致异构的结构弛豫。光致电子跃迁后的内建应力降低了玻璃基质随后结构重构的热活化势垒。我们提供了明确的预测的势垒分布和结构弛豫谱的光活化分子的浓度和材料的脆性的函数。典型的障碍光活化后减少，而障碍的分布增加的宽度与增加的摩尔分数的光活性分子和通量，并成为多模态。在冻结的玻璃中，光异构化的初始效应局部地促进了激发的发色团附近的动力学，并且可以在足够高的能量密度下导致完全流化。光子活化最初降低玻璃的屈服强度。然而，根据照明的精确时间过程，出现了软化区域与区域的空间共存，这些区域在被照明破坏后重新配置，使得它们现在由超稳定玻璃制成或像瓷器一样结晶。这一系列的事件，在照明后，可以导致高度稳定的无定形固体，潜在地接近Kauzmann极限。这些机制是在非晶材料的光学信息存储技术的根源。
We discuss the photon activation of structural relaxations in glassy melts and frozen glasses containing molecules that can photoisomerize. The built-in stress following a photoinduced electronic transition lowers the thermal activation barrier for subsequent structural reconfiguration of the glassy matrix. We provide explicit predictions for the barrier distribution and structural relaxation spectrum as functions of the concentration of photoactivated molecules and the fragility of the material. The typical barrier decreases upon photoactivation, while the barrier distribution increases in width with increasing mole fraction of photoactive molecules and fluence, and becomes multimodal. In a frozen glass, the initial effects of photoisomerization locally facilitate the dynamics near the excited chromophores and can lead to complete fluidization at a sufficiently high fluence. Photon activation initially decreases the yield strength of the glass. Depending on the precise time course of illumination, there however emerges a spatial coexistence of softened regions with regions that, after being destabilized by illumination, have reconfigured so that they are now made of ultrastable glass or have crystallized as in a porcelain. This sequence of events, after illumination, can lead to highly stable amorphous solids, potentially approaching the Kauzmann limit. These mechanisms are at the root of optical information storage technologies in amorphous materials.