液态水中氢键网络重排的能量学

Energetics of hydrogen bond network rearrangements in liquid water.

作者信息

Smith Jared D, Cappa Christopher D, Wilson Kevin R, Messer Benjamin M, Cohen Ronald C, Saykally Richard J

机构信息

Department of Chemistry, University of California, Berkeley, CA 94720, USA.

出版信息

Science. 2004 Oct 29;306(5697):851-3. doi: 10.1126/science.1102560.

DOI:10.1126/science.1102560

PMID:15514152

Abstract

A strong temperature dependence of oxygen K-edge x-ray absorption fine structure features was observed for supercooled and normal liquid water droplets prepared from the breakup of a liquid microjet. Analysis of the data over the temperature range 251 to 288 kelvin (-22 degrees to +15 degrees C) yields a value of 1.5 +/- 0.5 kilocalories per mole for the average thermal energy required to effect an observable rearrangement between the fully coordinated ("ice-like") and distorted ("broken-donor") local hydrogen-bonding configurations responsible for the pre-edge and post-edge features, respectively. This energy equals the latent heat of melting of ice with hexagonal symmetry (ice Ih) and is consistent with the distribution of hydrogen bond strengths obtained for the "overstructured" ST2 model of water.

摘要

对于由液体微射流破碎制备的过冷和正常液态水滴，观察到氧 K 边 X 射线吸收精细结构特征具有强烈的温度依赖性。对 251 至 288 开尔文（-22 摄氏度至 +15 摄氏度）温度范围内的数据进行分析，得出在完全配位（“类冰”）和扭曲（“断裂供体”）局部氢键构型之间实现可观察到的重排所需的平均热能值为每摩尔 1.5±0.5 千卡，这两种构型分别对应于前缘和后缘特征。该能量等于具有六方对称性的冰（冰 Ih）的熔化潜热，并且与水的“超结构”ST2 模型所获得的氢键强度分布一致。