Department of Applied Physics, Chalmers University of Technology, SE-412 96 Göteborg, Sweden.
Institut Laue Langevin, 6, rue Jules Horowitz, BP 156, 38042 Grenoble Cedex 9, France.
J Chem Phys. 2014 Mar 28;140(12):124501. doi: 10.1063/1.4868556.
Liquid monohydroxy alcohols exhibit unusual dynamics related to their hydrogen bonding induced structures. The connection between structure and dynamics is studied for liquid 1-propanol using quasi-elastic neutron scattering, combining time-of-flight and neutron spin-echo techniques, with a focus on the dynamics at length scales corresponding to the main peak and the pre-peak of the structure factor. At the main peak, the structural relaxation times are probed. These correspond well to mechanical relaxation times calculated from literature data. At the pre-peak, corresponding to length scales related to H-bonded structures, the relaxation times are almost an order of magnitude longer. According to previous work [C. Gainaru, R. Meier, S. Schildmann, C. Lederle, W. Hiller, E. Rössler, and R. Böhmer, Phys. Rev. Lett. 105, 258303 (2010)] this time scale difference is connected to the average size of H-bonded clusters. The relation between the relaxation times from neutron scattering and those determined from dielectric spectroscopy is discussed on the basis of broad-band permittivity data of 1-propanol. Moreover, in 1-propanol the dielectric relaxation strength as well as the near-infrared absorbance reveal anomalous behavior below ambient temperature. A corresponding feature could not be found in the polyalcohols propylene glycol and glycerol.
液态单羟醇表现出与其氢键诱导结构相关的异常动力学。使用准弹性中子散射，结合飞行时间和中子自旋回波技术，研究了液体 1-丙醇中结构与动力学之间的关系，重点是对应于结构因子主峰和前峰的长度尺度上的动力学。在主峰处，探测结构弛豫时间。这些与文献数据计算得出的力学弛豫时间非常吻合。在前峰处，与氢键结构相关的长度尺度相对应，弛豫时间长了几乎一个数量级。根据先前的工作[C. Gainaru、R. Meier、S. Schildmann、C. Lederle、W. Hiller、E. Rössler 和 R. Böhmer，Phys. Rev. Lett. 105, 258303 (2010)]，这种时间尺度差异与氢键簇的平均大小有关。基于 1-丙醇的宽频介电数据，讨论了中子散射和介电光谱法确定的弛豫时间之间的关系。此外，在 1-丙醇中，介电弛豫强度以及近红外吸收在环境温度以下表现出异常行为。在聚醇丙二醇和甘油中没有发现相应的特征。
