将晶体学与真实空间重新结合起来:使用4D-STEM阐明Ab initio结构
Ambarneil Saha1, Alexander J Pattison1, Karen C Bustillo1
1National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720.
概括
本研究引入了一种使用4D扫描传输电子显微镜的新方法,用于结合真实空间和衍射空间数据来确定晶体结构. 这种方法成功地解决了以前用传统方法难以处理的金属有机框架结构.
科学领域:
- 晶体学 晶体学是指结晶学.
- 材料科学 材料科学 材料科学
- 电子显微镜电子显微镜
背景情况:
- 传统的单晶结构阐明仅依赖于衍射空间数据.
- 在晶体学中,对实体空间信息的实验性访问是有限的.
- 聚合纳米结构对传统的微晶电子衍射构成了挑战.
研究的目的:
- 用4D扫描传输电子显微镜 (4D STEM) 将真实空间信息集成到晶体工作流中.
- 克服传统方法的局限性,以确定具有挑战性的纳米级材料的结构.
- 为了实现直接方法解决扫描纳米束电子衍射结构.
主要方法:
- 利用4D STEM的双空间成像能力.
- 使用通过细分高角度环状暗场图像 (HAADF) 创建的虚拟光圈.
- 从距离较近的纳米晶体中分离连贯的布拉格信号.
- 从标本的特定子区域选择性地提取集成强度.
主要成果:
- 布拉格信号与纳米晶体集群的像素对像素分离.
- 选择性强度提取用于调整多个散射器件.
- 从难以处理的样本中成功地解决了金属有机框架 UiO-66 的结构.
- 通过使用扫描纳米束电子衍射直接方法确定的亚光电流分辨率结构的演示.
结论:
- 开发的4D STEM战略有效地整合了现实空间和衍射空间数据以阐明结构.
- 这种方法可以选择最佳的纳米区域,以获得高质量的衍射数据.
- 它为解决纳米材料的晶体结构提供了一个强大的新方法,包括那些具有复杂形态的纳米材料.
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