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arXiv 2103.01935cond-mat.mtrl-scicond-mat.str-el
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β-Mn的结构手性

Structural Chirality of beta-Mn

S. W. Lovesey

摘要:

布拉格衍射的对映体对结构的理论研究应适用于使用共振增强的X射线衍射在β-Mn上收集的图案。手性多晶型的锰,结构相关的化合物,将更方便比三角晶体低石英,碲和berlinite在以前的结构研究中使用的这种类型,因为立方对称消除了一些复杂的吸收和宏观双折射校正。在光子Y(h,k,l)的初级束中通过圆偏振接合的布拉格点的强度被提出作为被照射材料的手性特征。部分强度需要所有四个偏振通道中的散射振幅的知识,其被报告为方位角(晶体围绕反射矢量的轴的旋转)的函数。与三方手性晶体不同,β-Mn的Y(0,0,l)= 0,并且它是(h,k,0)和对称性相关的布拉格斑点,其概括了结构手性。具体而言,反射矢量(h,k,0)与奇数米勒指数和β-Mn网的手性轴的螺旋度,与相应的Y(h,k,0)的大小相等,相反的符号的对映体对的合作伙伴。Y(h,k,0)对方位角的依赖性不反映立方晶体结构中的旋转对称的二分体或四分体轴。

英文摘要:

A theoretical study of Bragg diffraction by an enantiomorphic pair of structures should apply to patterns gathered on beta-Mn using resonance enhanced x-ray diffraction. The chiral polymorph of manganese, and structurally related compounds, will be more convenient than trigonal crystals of low-quartz, tellurium and berlinite used in previous structural studies of this type, because cubic symmetry removes some complications of correction for absorption and macroscopic birefringence. Intensity of a Bragg spot engaged by circular polarization in the primary beam of photons Y(h, k, l) is proposed as a chiral signature of the illuminated material. The partial intensity requires a knowledge of scattering amplitudes in all four channels of polarization, which are reported as functions of an azimuthal angle (rotation of the crystal about the axis of the reflection vector). Unlike trigonal chiral crystals, Y(0, 0, l) = 0 for beta-Mn and it is (h, k, 0), and symmetry related Bragg spots, that epitomize structural chirality. Specifically, reflection vectors (h, k, 0) with odd Miller indices and the chiral axis of beta-Mn mesh in terms of helicity, with the corresponding Y(h, k, 0) equal in magnitude and opposite in sign for partners in the enantiomorphic pair. Dependence of Y(h, k, 0) on the azimuthal angle does not mirror the dyad or tetrad axes of rotation symmetry in the cubic crystal structure.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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