IMPMC, Université P. et M. Curie et CNRS-UMR 7590, Paris, France.
J Chem Phys. 2011 Jan 21;134(3):034514. doi: 10.1063/1.3526939.
We present results of a series of experiments performed on LiBr, 6H(2)0 from room temperature down to 172 K ≈ 1.2T(g). These ultrasound, Brillouin and depolarized light scattering, and transient grating experiments show that, above 215 K, this solution behaves like supercooled water: its zero frequency sound velocity C(0) continuously decreases with decreasing temperature, and the reorientational dynamics of the water molecules can be directly detected at some temperatures of this domain. Conversely, below 215 K, a new regime sets in, where the apparent C(0) is practically temperature independent and where a β, Arrenhius like, relaxation process coexists with the usual, Vogel-Fulcher like, α relaxation process of the supercooled liquid. These results are similar to those recently obtained in LiCl, 6H(2)O. The onset of the new regime is possibly due to an increase of the interaction of the water molecules with a neighboring Li(+) ion when lowering the temperature. We also compare our results with published dielectric data on water solutions of glass forming polyalcohols. Some of them present a low temperature splitting of their relaxation time similar to what is found in LiBr, 6H(2)O.
我们呈现了在 LiBr、6H(2)0 上进行的一系列实验结果，实验温度从室温降至 172 K ≈ 1.2T(g)。这些超声、布里渊和退偏振光散射以及瞬态光栅实验表明，在 215 K 以上，该溶液的行为类似于过冷水：其零频声速 C(0)随着温度的降低连续减小，并且在该区域的某些温度下可以直接检测到水分子的重新取向动力学。相反，在 215 K 以下，新的状态开始出现，其中表观 C(0)实际上与温度无关，并且类似于常见的 Vogel-Fulcher 型α过冷液体松弛过程，β、阿伦尼乌斯型松弛过程共存。这些结果与最近在 LiCl、6H(2)O 中获得的结果相似。新状态的开始可能是由于温度降低时水分子与相邻 Li(+)离子相互作用的增加。我们还将我们的结果与已发表的玻璃形成多元醇水溶液的介电数据进行了比较。其中一些在低温下出现弛豫时间的分裂，类似于在 LiBr、6H(2)O 中发现的情况。
