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无定形分子系统的结构和结构弛豫。在这个两年的计划中，我们研究了由具有构象异构体的化合物制成的样品的弛豫，以阐明分子结构变化与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，以实现。在污染物较少的条件下对非晶样品进行了拉曼测量。沿着这一工作，我们尝试了对1，2-二氯乙烷（DCE）的测量，发现即使在固态非晶态下，DCE的笨拙分子也随着温度的升高而增加。从定量估计的gauche摩尔分数，我们发现，在样品表面上的室温蒸汽沉积的温度是小到几个开尔文。在温度升高的初始阶段，Gauche的增加速率很小，但在一定温度范围内，Gauche的增加速率加快，这取决于沉积温度。在此基础上，我们对非晶态DCE的弛豫过程进行了详细的讨论，并在J. Phys. Chem. B.我们还研究了无定形丁腈的松弛，具有构象异构体类似的DCE。在本研究中，我们发现在玻璃化转变温度T_g处，拉曼带的波数随温度的变化方向相反。这是第一次观察到的玻璃化转变是由光谱测量证实。我们在J.Non-Cryst.Solid.目前，我们正在进一步研究一个新的现象，即当我们在接近T_g的温度下制备样品时，其弛豫行为不同于普通的弛豫行为。

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.