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在超冷水中的转化扩散在玻璃过渡温度-136 K附近和附近
Greg A Kimmel1, Megan K Dunlap1, Kirill Gurdumov1
1Physical Sciences Division, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, USA.
The Journal of chemical physics
|June 24, 2025
概括
无形固态水在136K的玻璃过渡温度 (Tg) 附近呈现翻译扩散,表明它表现为强液体. 这项研究使用红外光谱学研究纳米水膜中的扩散混合.
科学领域:
- 物理化学 物理化学
- 材料科学是一种材料科学.
- 凝聚物质物理学 凝聚物质物理学
背景情况:
- 在其玻璃过渡温度 (Tg) 136 K附近的无形固态水的性质仍然是争论的主题.
- 竞争的假设表明,要么是一个真正的液态,具有转化扩散,要么只有旋转运动在Tg.变得活跃.
研究的目的:
- 调查纳米水膜中的扩散混合,以解决有关Tg附近水的特性争论.
- 为了确定转化扩散是否发生在热量计玻璃过渡温度和附近.
主要方法:
- 利用红外 (IR) 光谱学研究纳米水膜 (厚度高达~100纳米) 中的扩散混合.
- 使用同位素分层薄膜 (H2O与D2O) 来通过不同的红外光谱追踪混合.
- 在120-144K的温度范围内进行实验,确保最小的H/D交换.
主要成果:
- 在水膜 (20-100纳米厚) 中观察到120和144K之间的扩散混合,在结晶之前.
- 翻译扩散遵循阿雷尼乌斯温度依赖,激活能量为40.8 ± 3.5 kJ/mol.
- 在136 K的扩散系数测量为6.25±1.4 × 10^-21 m2/s.
结论:
- 观察到的转化扩散表明,无形固体水在其玻璃过渡温度 (Tg) 和附近的温度下表现为强液体.
- 这些发现支持了这样一个假设:在Tg时,水变为体,呈现出真正液体的特征.
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