液态水中第一个协调的结构
Ph Wernet1, D Nordlund, U Bergmann
1Stanford Synchrotron Radiation Laboratory, Post Office Box 20450, Stanford, CA 94309, USA.
概括
液态水分子主要存在于两个结合的配置中,而不是冰的四面体结构. 加热液态水会导致这些双键结构的微小转移.
科学领域:
- 物理化学 物理化学
- 材料科学 材料科学 材料科学
- 凝聚物质物理学 凝聚物质物理学
背景情况:
- 了解液态水的局部分子结构对于许多科学学科至关重要.
- 以前的研究通常依赖于间接方法或模拟,结果各不相同.
研究的目的:
- 为了研究液态水的第一个协调中的局部分子排列.
- 为了比较液态水与六角冰 (Ih) 的结构和模拟模型.
主要方法:
- 使用X射线吸收光谱 (XAS) 和X射线拉曼散射 (XRS).
- 将实验数据与散装和表面六角冰 (Ih) 进行比较,并进行理论计算.
主要成果:
- 液态水分子主要采用两种键配置,与冰的四面体结构不同.
- 一小部分 (5-10%) 的分子在从25°C加热到90°C时,从四面体转变为双键结构.
- 观察到与当前分子动力学模拟预测的结构存在重大差异.
结论:
- 液态水的局部结构的特点是特定的结安排.
- 实验发现为液态水结构模型提供了严格的约束.
- 目前的分子动力学模拟可能需要改进,以准确地表示液态水的局部结构.
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