Precession technique and electron diffractometry as new tools for crystal structure analysis and chemical bonding determination
- 作者：A. Avilov ; K. Kuligin ; S. Nicolopoulos ; M. Nickolskiy ; K. Boulahya ; J. Portillo ; G. Lepeshov ; B. Sobolev ; J.P. Collette ; N. Martin ; et al.
- 关键词：Electron diffractometer ; Electron beam precession ; Chemical bonding ; Electrostatic potential distribution
- 刊名：Ultramicroscopy
- 出版年：2007
- 期刊代码：79_03043991
- 类别：ph
- 出版时间：June-July 2007
- 卷：107
- 期：6-7
- 页码：431-444
- 文件大小：923 K
摘要
We have developed a new fast electron diffractometer working with high dynamic range and linearity for crystal structure determinations. Electron diffraction (ED) patterns can be scanned serially in front of a Faraday cage detector; the total measurement time for several hundred ED reflections can be tens of seconds having high statistical accuracy for all measured intensities (1–2%). This new tool can be installed to any type of TEM without any column modification and is linked to a specially developed electron beam precession “Spinning Star” system. Precession of the electron beam (Vincent–Midgley technique) reduces dynamical effects allowing also use of accurate intensities for crystal structure analysis. We describe the technical characteristics of this new tool together with the first experimental results. Accurate measurement of electron diffraction intensities by electron diffractometer opens new possibilities not only for revealing unknown structures, but also for electrostatic potential determination and chemical bonding investigation. As an example, we present detailed atomic bonding information of CaF2 as revealed for the first time by precise electron diffractometry.