低剂量电子显微表征下的出射波重构技术

Exit wave reconstruction in low⁃dose electron microscopy

原子级分辨率的成像表征对探究材料结构与性质间的联系具有重大意义。应用像差校正的高分辨电子显微成像技术(high⁃resolution transmission electron microscopy,HRTEM)可以实现亚埃尺度分辨率的图像表征,但电子束辐照敏感材料受限于辐照引起的结构损伤,无法用常规辐照剂量进行HRTEM成像表征。将出射波重构(exit wave reconstruction,EWR)技术应用于辐照敏感材料,一方面可以解决HRTEM图像中衬度反转的问题并提高图像分辨率至信息极限;另一方面,通过算法实现对信息的充分利用,适合于从低剂量数据中提取有效信息。采用低剂量EWR技术可以实现电子束敏感材料的原子级分辨率图像,为研究电子束辐照敏感材料提供更多可能性,也使针对出射波重构技术的研究具有更大的应用前景与科学意义。

Atomic⁃resolution imaging is of great significance for investigating the relationship between structure and property of a material.The resolution of high⁃resolution transmission electron microscopy(HRTEM)has been improved to the sub-Ångstrom level using aberration correctors for all materials except for beam⁃sensitive ones,which are limited by their critical electron dose and dose⁃rate.Exit wave reconstruction(EWR)could be applied to avoid the contrast variation and to improve the resolution to the information limit.More importantly,the algorithm fully utilizes the collected information,which is suitable for low⁃dose imaging.Atomic⁃resolution imaging for beam⁃sensitive materials has been attained by low⁃dose EWR technique,which offers more options for structural study of beam⁃sensitive materials.