用X波段电子顺磁共振(EPR)谱研究了氮氧自由基自旋探针在乙醇玻璃和结晶乙醇中的光谱性质。在两个主机矩阵的不同的各向异性的分子包装证明了不同的刚性极限值的最大超精细分裂的自旋探针的信号。与乙醇玻璃相比,溶解在结晶乙醇中的自旋探针的相记忆时间显著缩短,从光谱扩散的贡献方面进行了讨论。低频动力学的影响表现在温度的依赖性和在不同的光谱位置测量的数据之间的差异。这一现象是在慢运动各向同性扩散模型的框架内解决的[S. Lee和S. Z. Tang,Phys.Rev.B31,1308(1985)],预测在极低温度下毫秒范围内的自旋探针动力学。自旋探针在乙醇玻璃中的自旋-晶格弛豫时间较短,这是由于玻色子峰激发增强了玻璃基质中自旋系统与晶格之间的能量交换。
英文摘要:
X-band electron paramagnetic resonance (EPR) spectroscopy was used to study the spectral properties of a nitroxide spin probe in ethanol glass and crystalline ethanol, at 5 - 11.5 K. The different anisotropy of molecular packing in the two host matrices was evidenced by different rigid limit values for maximal hyperfine splitting in the signal of the spin probe. The significantly shorter phase memory time, , for the spin probe dissolved in crystalline ethanol, as compared to ethanol glass, was discussed in terms of contribution from spectral diffusion. The effect of low-frequency dynamics was manifested in the temperature dependence of and in the difference between the data measured at different spectral positions. This phenomenon was addressed within the framework of the slow-motional isotropic diffusion model [S. Lee, and S. Z. Tang, Phys. Rev. B 31, 1308 (1985)] predicting the spin probe dynamics within the millisecond range, at very low temperatures. The shorter spin-lattice relaxation time of the spin probe in ethanol glass was interpreted in terms of enhanced energy exchange between the spin system and the lattice in the glass matrix due to boson peak excitations.
A swollen phase observed between the liquid-crystalline phase and the interdigitated phase induced by pressure and/or adding ethanol in DPPC aqueous solution
Institute of Nuclear Physics, Polish Academy of Sciences(波兰科学院核物理研究所);Institute of Chemistry, Military University of Technology(军事科技大学化学研究所);Faculty of Chemistry, Jagiellonian University(雅盖隆大学化学学院);Research Center for Thermal and Entropic Science, Graduate School of Science, Osaka University(大阪大学理学研究科热力学与熵科学研究中心)
Topological Description of the Solidification of Undercooled Fluids and the Temperature Dependence of the Thermal Conductivity of Crystalline and Glassy Solids Above Approximately 50 K
The boson peak in structural and orientational glasses of simple alcohols: Specific heat at low temperatures
在这项工作中,我们审查比热实验,我们已经进行了不同的氢键玻璃在过去几年中。具体来说,我们已经测量了一组玻璃醇的低温比热Cp:正常和全氘代乙醇,1-和2-丙醇,和甘油。乙醇表现出非常有趣的多态性,在低温下呈现三种不同的固相:完全有序(单斜)晶体,取向无序(立方)晶体或“取向玻璃”,以及普通结构玻璃。通过测量和比较三个相在玻色子峰2-10 K以及低于1 K的隧穿态范围内的低温比热,我们能够定量地证实“玻璃化行为”不是非晶态固体独有的性质。另一方面,丙醇是最简单的一元醇,具有两种不同的立体异构体(1-丙醇和2-丙醇),这使我们能够直接研究原子的空间重排对玻璃普遍性质的影响。我们已经测量了这两种异构体的比热,发现它们之间有一个值得注意的数量差异。最后,还获得了玻璃态甘油的低温比热数据。在这里,我们提出了一个简单的方法的基础上的软势模型来分析低温比热测量,我们用这种方法的定量比较所有这些数据的玻璃醇和作为一个严格的测试的几个普遍的相关性和标度律在文献中提出的。特别地,我们发现玻色子峰的双折射模型[A. V. Granato,Phys. Rev. Lett. 68(1992)974]很好地解释了Cp/T^3出现最大值时的温度。
Selective reflection of light in glassforming ternary liquid crystalline mixtures
Institute of Nuclear Physics, Polish Academy of Sciences(波兰科学院核物理研究所);AGH University of Cracow(克拉科夫AGH科技大学);Faculty of Materials Science and Ceramics, AGH University of Cracow(克拉科夫AGH科技大学材料科学与陶瓷学院);Jagiellonian University(雅盖隆大学);Faculty of Chemistry, Jagiellonian University(雅盖隆大学化学系);Military University of Technology(军事理工大学);Institute of Chemistry, Military University of Technology(军事理工大学化学研究所);Osaka University(大阪大学);Graduate School of Science, Osaka University(大阪大学理学研究科);Research Center for Thermal and Entropic Science, Graduate School of Science, Osaka University(大阪大学理学研究科热与熵科学研究中心)
Disorder-induced vibrational anomalies from crystalline to amorphous solids
玻色子峰是玻色子态密度超过德拜模型的一种现象,玻色子峰的起源至今仍有很大争议,其中一些理论和实验认为玻色子峰与van-Hove奇点有关。在这里,我们表明,玻色子峰和范霍夫奇点分离的身份,通过测量的振动密度的状态的二维颗粒系统,包装逐渐从晶体,多晶,和非晶材料的调整。我们观察到在多晶体中存在分离良好的玻色子峰和van-Hove奇异点,其中van-Hove奇异点逐渐向高频移动,同时形状变宽,当结构无序度$η$足够高时,van-Hove奇异点完全消失.通过对强无序系统($η=1$)和无序颗粒晶体($η=0$)以及$η$介于两者之间的中间无序系统的分析,发现玻色子峰与剪切模量$δG/\langle G \rangle$的空间不相关随机涨落有关,而van-Hove奇异性的涂抹与剪切模量$δG/\langle G \rangle$的空间相关涨落有关。
Multiple glassy dynamics of a homologous series of triphenylene-based columnar liquid crystals -- A study by broadband dielectric spectroscopy and advanced calorimetry