Light Scattering Studies of Supercooled Water (Chemistry)

计划对过冷水和水溶液进行光散射实验，以阐明导致过冷水热力学异常的结构机制。从这项工作中获得的拉曼数据将获得过冷水的直接结构信息。OH伸缩模将产生包括氢键几率、平均O-O分离和分布在内的最近邻信息。低频分子间模式将产生关于第二邻近壳层的信息，在该壳层中，与过冷异常相关的最显著的结构变化被认为发生了。光子相关光谱测量将被用来提取由于多个水分子之间的合作行为而产生的有效密度关联长度。水在地球表面的重要性怎么强调都不为过。这种重要性来自两个来源：其丰富，以及其独特的物理和化学性质。在过去的十年里，人们发现液态水在摄氏零度以下的过冷区域甚至更不寻常。在这里，它显示了它的热力学和输运性质的异常，可能正在接近奇点。水的关键在于它的氢键结构。拉曼光谱可以提供有关结构和动力学的微观信息。它可以确定氢键的程度，做出关于冰状或笼状结构的决定，并提供关于第一邻近壳层和分子簇的信息。

Light scattering experiments are planned for supercooled water and aqueous solutions to elucidate the structural mechanisms responsible for thermodynamic anomalies in supercooled water. Raman data obtained from this work will have direct structural information for supercooled water. The OH stretch modes will yield nearest neighbor information including hydrogen bond probability, and mean O-O separation and distribution. The low frequency intermolecular modes will yield information regarding the second neighbor shell wherein the most dramatic structural changes relevant to the supercooled anomalies are thought to occur. The photon correlation spectroscopy measurements will be used to extract effective density correlation lengths due to cooperative behavior between many water molecules. Water's importance on the face of the earth cannot be overstated. This importance stems from two sources: its abundance, and its unique physical and chemical properties. In the past decade it has been found that liquid water is even more unusual in the supercooled regime below zero degrees Centigrade. Here it displays anomalies in its thermodynamic and transport properties which may be approaching a singularity. The key to water is in its hydrogen bonded structure. Raman spectroscopy can give microscopic information regarding structure and dynamics. It can determine the extent of hydrogen bonding, make decisions regarding ice-like or clathrate structures, and give information on both the first neighbor shell and molecular clustering.