奈米級晶體同調性電子繞射影像之研究

Study of Nano-Particle By Coherent Electron Diffraction

馮祺凱(Chi-Kai Feng)

指導教授 ： 陳福榮 ； 開執中

國立清華大學/原子科學院/工程與系統科學系/碩士(2007年)

https://doi.org/10.6843/NTHU.2007.00666

摘要

同調性繞射影像技術(CDI)提供了一個可行的途徑：針對非週期性及有限大小的獨立奈米結構，此技術可得到原子尺寸之解析度影像。其概念是：經過物體的出口波函數可以在光學上透過超取樣(oversampling)出口波的遠場繞射圖樣，以及多次重複性的演算法回復其波函數。實驗上，我們透過電子顯微鏡拍攝單獨奈米級氧化鎂顆粒(大小約24nm的立方體)的[001]方向電子繞射圖樣，透過JOEL 2010F場發射式穿透電子顯微鏡，操作在200KeV的加速電子電壓以及奈米級電子束的條件下，我們藉著動態邊界(support)的相位回復的演算法，得到與高解析電子顯微影像相吻合的回復結果。

關鍵字

同調性繞射影像 ； 相位復原 ； 相位重建 ； 超取樣方法

並列摘要

The coherent diffractive imaging (CDI) technique offers a promising path toward characterization of the individual non-periodic and near-periodic isolated nanostructures at the atomic resolution. In this aberration-free microscopy, the complex exit surface wave function can be recovered from the over-sampled far-field diffraction pattern using iterative algorithms. We have recorded the image and diffraction pattern of the individual MgO nano-particle with a size of about 24nm with a crystallographic orientation [001] along the incident electron beam. The FEG-TEM (JEOL 2010F) was operated at 200keV accelerating voltage in the nano-area electron diffraction regime. For the reconstruction we utilized the phase-retrieval algorithm with dynamically defined support. The result is in agreement with the TEM image of the particle.

並列關鍵字

Coherent Diffrction Imaging ； phase retrieval ； phase reconstruction ； oversampling method ； Difference map method

參考文獻

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