Structural relaxation in amorphous molecular systems' Studies with conformation

我们一直在研究通过气相沉积在冷衬底上制备的非晶态分子体系的结构和结构弛豫。在这个为期两年的项目中，我们研究了具有构象异构体的化合物的样品的弛豫，以阐明分子结构变化和分子间构型变化之间的相互关系。在第一年，我们改进了真空系统来进行研究。在污染较少的条件下，对非晶态样品进行了拉曼光谱测量。在这项工作的同时，我们尝试了对1，2-二氯乙烷(DCE)的测量，发现即使在固体无定形状态下，DCE的笨拙分子也随着温度的升高而增加。第二年，我们继续对DCE进行了详细的研究。从Guche摩尔分数的定量估算中，我们发现样品表面沉积室温蒸汽的温度很小，甚至只有几个开尔文。在温度升高的初期，Guche的增长速度较小，但在一定的温度范围内随沉积温度的升高而加快。考虑到这些实验结果，我们对非晶态DCE的松弛过程进行了详细的讨论，并在《物理化学》杂志上报道了这一结果。我们还研究了构象异构体类似于DCE的非晶丁腈的松弛过程。在本研究中，我们发现在玻璃化转变温度T_g处，拉曼光谱波数的温度变化方向相反，这是第一次用光谱测量来证实玻璃化转变的观测结果。我们在J.Non-Cryst.Solid上报道了这些结果。目前，我们正在进一步研究一种新的现象，即在接近T_g的温度下制备的样品的弛豫行为不同于普通的松弛行为。

We have been studying structure and structural relaxation in amorphous molecular systems prepared by vapor deposition onto cold substrates. In this two-years project, we have studied the relaxation of samples made of compounds that have conformation isomers to elucidate the interrelation between the molecular structural change and the change in intermolecular configuration.In the first year, we improved the vacuum system to carry out the. Raman measurements on the amorphous samples under the condition with less amount of the contamination. Along with this work, we tried the measurements on 1,2-dichloroethan (DCE), and found interesting phenomena that the gauche molecules of DCE increased with the temperature elevation even in the solid amorphous states.In the second year, we continued the study on DCE in detail. From the quantitative estimation of the gauche mole fraction, we found that the temperature at the sample surface on deposition of room-temperature vapor was as small as few Kelvin. The rate of the increase of gauche was small in the initial period of temperature elevation, but it was accelerated above a certain region of temperature depending on the deposition temperature. Taking all such experimental results into consideration, we made a detail discussion on the relaxation process of amorphous DCE, and reported it in J.Phys.Chem.B. We also studied the relaxation of amorphous butyronitrile that has conformation isomers similar to those of DCE. In this study, we found that the temperature change of the wavenumber of a Raman-band turned to the opposite direction at the glass-transition temperature T_g. This was the first observation by which a glass transition was confirmed by spectroscopic measurements. We reported these results in J.Non-Cryst.Solid. For the moment, we are further studying a new phenomena that the relaxation behavior is different from ordinary ones when we prepare the samples at temperatures close to T_g.