Physical Sciences Division, Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA 99352, USA.
Science. 2020 Sep 18;369(6510):1490-1492. doi: 10.1126/science.abb7542.
A fundamental understanding of the unusual properties of water remains elusive because of the limited data at the temperatures and pressures needed to decide among competing theories. We investigated the structural transformations of transiently heated supercooled water films, which evolved for several nanoseconds per pulse during fast laser heating before quenching to 70 kelvin (K). Water's structure relaxed from its initial configuration to a steady-state configuration before appreciable crystallization. Over the full temperature range investigated, all structural changes were reversible and reproducible by a linear combination of high- and low-temperature structural motifs. The fraction of the liquid with the high-temperature motif decreased rapidly as the temperature decreased from 245 to 190 K, consistent with the predictions of two-state "mixture" models for supercooled water in the supercritical regime.
由于在决定竞争理论时所需的温度和压力下的数据有限，因此对水的异常性质的基本理解仍然难以捉摸。我们研究了在快速激光加热过程中每脉冲几纳秒加热的过冷水膜的结构转变，然后将其淬火至 70 开尔文 (K)。在明显结晶之前，水的结构从初始构型松弛到稳定构型。在所研究的整个温度范围内，所有结构变化都是可逆的，可以通过高温和低温结构基序的线性组合来重现。随着温度从 245 降至 190 K，具有高温基序的液体分数迅速减少，这与超临界区过冷水的两态“混合物”模型的预测一致。
