在玻璃过渡附近直接观察分子合作性
1Department of Physics and Center for Interdisciplinary Research on Complex Systems, Northeastern University, Boston, Massachusetts 02115, USA.
Nature
|December 29, 2000
概括
研究人员观察到聚乙酸 (PVAc) 在玻璃过渡附近的分子合作性. 个别的分子集群显示了短暂的动态异质性和非指数动力学,为玻璃动力学提供了新的见解.
科学领域:
- 材料科学 材料科学 材料科学
- 物理化学 物理化学
- 凝聚物质物理学 凝聚物质物理学
背景情况:
- 玻璃动力学,以玻璃过渡附近的缓慢分子反应为特征,在蛋白质和超导体等多种系统中观察到.
- 合作分子重新排列已被理论化解释放松时间和眼镜中的反应功能.
- 之前的研究在合玻璃和模拟中观察到合作性,但对分子玻璃过渡的直接纳米尺度洞察力缺失.
研究的目的:
- 在分子玻璃过渡过程中直接观察和分析分子合作性.
- 调查合作的长度尺度和形式.
- 确定扩展响应功能是否本质上来自合作区域或集体异质性.
主要方法:
- 使用纳米尺度探测介电波动.
- 分析了来自分子团的随机电报噪声信号及其功率光谱.
- 在其玻璃过渡附近研究了聚乙烯酸 (PVAc).
主要成果:
- 在玻璃过渡附近,直接观察到聚乙酸 (PVAc) 中的分子合作性.
- 确定了分子集,自发地在2-4个配置之间切换,产生随机电报噪声.
- 证明单个集群表现出暂时的动态异质性和非指数动力学.
结论:
- 个别的合作区域表现出内在的瞬态动态异质性和非指数动力学.
- 在玻璃过渡过程中提供了分子合作性的纳米级直接证据.
- 进步了对玻璃动态背后的基本机制的理解.
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