Hecksher Tina, Jakobsen Bo
DNRF Centre "Glass and Time", IMFUFA, Department of Sciences, Roskilde University, Postbox 260, DK-4000 Roskilde, Denmark.
J Chem Phys. 2014 Sep 14;141(10):101104. doi: 10.1063/1.4895095.
A recent study [C. Gainaru, R. Figuli, T. Hecksher, B. Jakobsen, J. C. Dyre, M. Wilhelm, and R. Böhmer, Phys. Rev. Lett. 112, 098301 (2014)] of two supercooled monohydroxy alcohols close to the glass-transition temperature showed that the Debye peak, thus far mainly observed in the electrical response, also has a mechanical signature. In this work, we apply broadband shear-mechanical spectroscopy to a systematic series of octanol structural isomers, x-methyl-3-heptanol (with x ranging from 2 to 6). We find that the characteristics of the mechanical signature overall follow the systematic behavior observed in dielectric spectroscopy. However, the influence from the molecular structure is strikingly small in mechanics (compared to roughly a factor 100 increase in dielectric strength) and one isomer clearly does not conform to the general ordering. Finally, the mechanical data surprisingly indicate that the size of the supramolecular structures responsible for the Debye process is nearly unchanged in the series.
最近一项针对接近玻璃化转变温度的两种过冷单羟基醇的研究[C. 盖纳鲁、R. 菲古利、T. 赫克舍尔、B. 雅各布森、J. C. 戴尔、M. 威廉和R. 伯默，《物理评论快报》112, 098301 (2014)]表明，德拜峰迄今为止主要在电响应中被观测到，它也具有机械特征。在这项工作中，我们将宽带剪切机械光谱学应用于一系列系统的辛醇结构异构体，即x - 甲基 - 3 - 庚醇（x取值范围为2至6）。我们发现，机械特征的特性总体上遵循在介电光谱学中观测到的系统行为。然而，分子结构在力学方面的影响非常小（与介电强度大约增加100倍相比），并且有一种异构体明显不符合一般的排序规律。最后，机械数据令人惊讶地表明，在该系列中，负责德拜过程的超分子结构的尺寸几乎没有变化。
