鎖状分子の固態内分子回転と核磁気共鳴

概要

論文の詳細を見る
The hindered rotational motion in the solid state of long chain molecules is discussed from the experimental investigation of nuclear magnetic resonance in the piled-up crystals of cetyl alcohol (CH_3(CH_2)_<15>OH) and from the measurements of T_1 in its powder specimen. It is considered that, in the piled-up crystals of cetyl alcohol, long chain axes of molecules are perpendicular to the thin plate and are parallel to each other in the rotating state. The experimental absorption lines for protons in these specimen are given for the various directions of the specimen to the static magnetic field. Temperatures ranged from room temperature to just below the melting point of cetyl alcohol. At and above the transition point, narrowing of the absorption line width occurs. The magnitude of deduction of line width depends on the direction of the specimen. In the rigid state, two different types of angular dependence of line shape were found by possibly different heat treatments of the specimen. The second moment analysis suggests that one belongs to monoclinic system and the other to orthorhombic. In the rotating state, the experimental second moment of the absorption line depends on the direction of the specimen. The theoretical value was calculated, based upon the molecular rotation about long chain axes. The agreement between the observed values and the theoretical ones is fairly close. It can be concluded that the piled-up specimen of single crystals gives a more detailed information about the molecular rotation than the powder pecimen. The spin lattice relaxation times T_1 were measured in the rotating state of both the piled-up specimen and the powder one. In the powder specimen, T_1 has a minimum value at the temperature of 46℃ for the frequency of 30 MC/S. Angular dpendence of T_1 in the piled-up specimen was not so clear because of the experimental error. From the comparison between the experimental results and the theoretical consideration of these relaxation times, the following mechanism on the molecular motion in the rotating state was suggested. The potential barrier for the hindered rotation of molecules would not be invariable. Molecules would be sometimes in the reorientational state with a long correlation time, and frequently in the state with a short correlation time.
明治大学の論文

著者

小松八郎
明治大学

鎖状分子の固態内分子回転と核磁気共鳴

スポンサーリンク

概要

著者

関連論文

スポンサーリンク