Realization of a two-dimensional glass, and the direct observation of its ordered-cluster structure and structural change

由于分子的排列基本上是无序的，过冷液体和过冷玻璃的科学还没有得到足够的发展。而分子聚集过程中有序性的发展对其低温特性起着重要的作用。我们针对这些系统的结构提出了一个“有序簇聚集模型”。在本研究中，首先尝试实现二维玻璃并直接观察分子聚集及其变化，然后基于所提出的模型发现或阐明新的现象。1)构建了一种在液氮温度下工作的扫描隧道显微镜。发现了沉积在石墨表面的邻特苯分子，但尚未成功地形成并观察其单层玻璃。2)用介电法研究了简单苯衍生物的α和β弛豫时间，以及取代基在1 -和3-多个位置上的系统变化。β弛豫时间与异丙基内取代基的大小和氢键形成基团-OH和NH_2的存在与否无关，而α弛豫时间则与这些因素密切相关。α玻璃化过渡区β弛豫强度明显大于快速冷却区。3) 7个含苯基环的化合物共发现了基于核的均匀结晶，说明苯基环的存在对其观察具有重要意义。还指出，晶体核的取向应与原晶体的取向一致，这对观察是重要的。4)当液体从熔点以上迅速冷却到α玻璃化转变温度以下时，邻苯基苯酚开始结晶成核。发现在一定温度范围内，晶核形成，然后熄灭，经过较长时间后再次形成。5)在三苯基亚磷酸酯中，除存在正常液相（L_N）相外，还存在非晶态（L_C）相。基于L_N和L_C相的α弛豫性质，讨论了α分子重排过程一般由两个相对独立的因素控制：结构有序簇的大小和簇的有序程度，而弛豫时间基本由后者决定。少

Science of Supercooled liquids and glasses has not been developed enough because of the aspect that the arrangement of molecules is essentially disordered. The development of ordering in the molecular aggregation, however, plays an important role in their characteristic properties at low temperatures. We have proposed an "ordered-clusters aggregation model" for the structure of those systems. In this research, it was tried first to realize a two-dimensional glass and observe directly the molecular aggregation and its change, and second to discover or elucidate new phenomena based on the proposed model.1) A scanning tunneling microscope was constructed which works at liquid nitrogen temperature. o-Terphenyl molecules deposited on a graphite surface was identified, but it has not been succeeded yet to form and observe its mono-layer glass.2) α and β relaxation times of simple benzene-derivatives were investigated dielectrically with systematic change of the substituent groups at 1 and 3- … More positions. While the β relaxation times were rather independent of the size of substituents to within isopropyl group and the presence/absence of hydrogen-bond forming, -OH and NH_2, groups, α relaxation times depended strongly on those factors. The β relaxation strength was appreciably large in the sample cooled rapidly than slowly in the α glass transition region in advance.3) Homogeneous-nucleation-based crystallization was found in total in seven compounds with phenyl rings, indicating that the presence of the ring is important for its observation. It was also indicated to be important for the observation that the orientation of the crystal nucleus should coincide with that of the original crystal.4) Crystal nucleation was followed for o-benzylphenol after the liquid was cooled very rapidly from above fusion point to below the α glass transition temperature. It was found in a certain temperature region that the crystal nuclei were formed, then extinguished, and formed again after further long duration.5) In addition to a normal liquid (L_N) phase, another amorphous (L_C) phase was confirmed to exist in triphenylphosphite. Based on the α relaxation properties of the L_N and L_C phases, it was discussed that, in general, the α molecular rearrangement process is controlled by two relatively independent factors : the size of structurally ordered cluster and the degree of the order in the cluster, and that the relaxation time is basically determined by the latter factor. Less