Molecular dynamics in perfluoro‐n‐eicosane. I. Solid phase behavior and crystal structures
Molecular dynamics in perfluoro‐n‐eicosane. I. Solid phase behavior and crystal structures
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全氟正二十烷的分子动力学 I. 固相行为和晶体结构。
DOI：
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发表时间：
1991
期刊：
影响因子：
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通讯作者：
M. Kimmig
中科院分区：
文献类型：
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作者：
H. Schwickert;G. Strobl;M. Kimmig
全氟正二十烷（n-C20 F42）经过三种不同的固体改性，称为M（T 200 K）。通过X射线散射实验表征相M和R的结构。晶体是由矩形层构成的。在修改M层是由右手和左手（15/7-）螺旋阵列交替连续设置。晶胞为单斜晶系（a=9.65 A，B=5.70 A，c=28.3 A，β=97°;空间群Pa）。在修饰中，R分子是高度移动的。关于螺旋旋向没有顺序。分子类似于圆柱形物体，并以六边形密集模式堆积。规则的层堆叠导致晶体具有菱面体对称性（a=B=5.70 A，c=85.00 A，γ=120°;空间群R3 m）。
Perfluoro‐n‐eicosane (n‐C20F42) passes through three different solid modifications, called M(T 200 K). Structures of the phases M and R were characterized by x‐ray scattering experiments. Crystals are built up by rectangular layers. In modification M layers are set up by arrays of right‐handed and left‐handed (15/7‐) helices in alternate succession. The unit cell is monoclinic (a=9.65 A, b=5.70 A, c=28.3 A, and β=97°; space group Pa). In modification R molecules are highly mobile. There is no ordering with regard to the helix handedness. Molecules resemble cylindrical objects and are packed in a hexagonal dense mode. Regular layer stacking results in crystals with rhombohedral symmetry (a=b=5.70 A, c=85.00 A, γ=120°; space group R3m).