School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, USA.
J Chem Phys. 2017 Feb 14;146(6):064501. doi: 10.1063/1.4975389.
On the basis of adiabatic calorimetry data and results obtained from dielectric relaxation studies in the presence of a high static electric field, the effects of temperature and electric field induced changes of the excess entropy are compared for the same sample: supercooled cresolphthalein dimethylether. A field induced reduction of the excess entropy by 45 mJ K mol at constant temperature increases the structural relaxation time by 0.75%, while the same entropy change originating from lowering the temperature at constant field increases the time constant by 3.5%. Therefore, there is no simple link connecting excess entropy and relaxation time that is independent of the control parameter that is used to modify the entropy. A consequence is that the Adam-Gibbs approach does not provide a quantitative prediction for how the dynamics of liquids depend on the electric field, and, more generally, on excess entropy. This work compares the dynamics for temperature versus field induced changes of isobaric excess entropy, thereby eliminating previous uncertainties arising from isochoric versus isobaric conditions and from unknown relations between thermodynamic, excess, and configurational entropies.
基于绝热量热法数据和在高静电场存在下介电松弛研究的结果，比较了相同样品：过冷甲酚紫二甲醚的过剩熵的温度和电场诱导变化的影响。在恒温下，过剩熵减少 45 mJ K mol 会使结构弛豫时间增加 0.75%，而在恒电场下由降低温度引起的相同熵变会使时间常数增加 3.5%。因此，没有简单的关系将过剩熵与弛豫时间联系起来，而这种关系与用于改变熵的控制参数无关。其结果是，Adam-Gibbs 方法不能提供关于液体动力学如何依赖于电场的定量预测，更一般地说，不能提供关于过剩熵的预测。这项工作比较了温度与等压过剩熵的场诱导变化之间的动力学，从而消除了以前由于等容与等压条件以及热力学、过剩和构象熵之间未知关系而产生的不确定性。
