J Chem Phys. 2011 Oct 28;135(16):167102. doi: 10.1063/1.3647898.
Very recently Kwon et al. [H.-J. Kwon, J.-A. Seo, H. K. Kim, and Y. H. Hwang, J. Chem. Phys. 134, 014508 (2011)] published an article on the study of dielectric relaxation in trehalose and maltose glasses. They carried out broadband dielectric measurements at very wide range of temperatures covering supercooled liquid as well as glassy state of both saccharides. It is worth to mention that authors have also applied a new method for obtaining anhydrous glasses of trehalose and maltose that enables avoiding their caramelization. Four relaxation processes were identified in dielectric spectra of both saccharides. The slower one was identified as structural relaxation process the next one, not observed by the others, was assigned as Johari-Goldstein (JG) β-relaxation, while the last two secondary modes were of the same nature as found by Kaminski et al. [K. Kaminski, E. Kaminska, P. Wlodarczyk, S. Pawlus, D. Kimla, A. Kasprzycka, M. Paluch, J. Ziolo, W. Szeja, and K. L. Ngai, J. Phys. Chem. B 112, 12816 (2008)]. In this comment we show that the authors mistakenly assigned the slowest relaxation process as structural mode of disaccharides. We have proven that this relaxation process is an effect of formation of thin layer of air or water between plate of capacitor and sample. The same effect can be observed if plates of capacitor are oxidized. Thus, we concluded that their slowest mode is connected to the dc conduction process while their β JG process is primary relaxation of trehalose and maltose.
最近，Kwon 等人[H.-J. Kwon、J.-A. Seo、H. K. Kim 和 Y. H. Hwang，J. Chem. Phys. 134, 014508 (2011)]发表了一篇关于海藻糖和麦芽糖玻璃中介电弛豫研究的文章。他们在非常宽的温度范围内进行了宽带介电测量，涵盖了这两种糖的过冷液体和玻璃态。值得一提的是，作者还应用了一种新方法来获得海藻糖和麦芽糖的无水玻璃，从而避免了它们的焦糖化。在这两种糖的介电谱中，共识别出了四个弛豫过程。较慢的一个被识别为结构弛豫过程，下一个，其他作者没有观察到，被分配为 Johari-Goldstein (JG) β 弛豫，而最后两个次级模式与 Kaminski 等人发现的相同[K. Kaminski、E. Kaminska、P. Wlodarczyk、S. Pawlus、D. Kimla、A. Kasprzycka、M. Paluch、J. Ziolo、W. Szeja 和 K. L. Ngai，J. Phys. Chem. B 112, 12816 (2008)]。在这个评论中，我们表明作者错误地将最慢的弛豫过程分配为二糖的结构模式。我们已经证明，这个弛豫过程是在电容器板和样品之间形成薄层空气或水的结果。如果电容器板被氧化，也可以观察到相同的效果。因此，我们得出结论，它们最慢的模式与直流传导过程有关，而它们的β JG 过程是海藻糖和麦芽糖的主要弛豫过程。
