Morishita Shigeyuki, Kohno Yuji, Hosokawa Fumio, Suenaga Kazu, Sawada Hidetaka
JEOL Ltd., 3-1-2 Musashino, Akishima, Tokyo 196-8558, Japan.
BioNet Laboratory Inc., 2-3-28 Nishiki-chou, Tachikawa, Tokyo 190-0022, Japan.
Microscopy (Oxf). 2018 Jun 1;67(3):156-163. doi: 10.1093/jmicro/dfy009.
Higher order geometrical aberration correctors for transmission electron microscopes are essential for atomic-resolution imaging, especially at low-accelerating voltages. We quantitatively calculated the residual aberrations of fifth-order aberration correctors to determine the dominant aberrations. The calculations showed that the sixth-order three-lobe aberration was dominant when fifth-order aberrations were corrected by using the double-hexapole or delta types of aberration correctors. It was also deduced that the sixth-order three-lobe aberration was generally smaller in the delta corrector than in the double-hexapole corrector. The sixth-order three-lobe aberration was counterbalanced with a finite amount of the fourth-order three-lobe aberration and 3-fold astigmatism. In the experiments, we used a low-voltage microscope equipped with delta correctors for probe- and image-forming systems. Residual aberrations in each system were evaluated using Ronchigrams and diffractogram tableaux, respectively. The counterbalanced aberration correction was applied to obtain high-resolution transmission electron microscopy images of graphene and WS2 samples at 60 and 15 kV, respectively.
透射电子显微镜的高阶几何像差校正器对于原子分辨率成像至关重要，尤其是在低加速电压下。我们定量计算了五阶像差校正器的残余像差，以确定主要像差。计算结果表明，当使用双六极或δ型像差校正器校正五阶像差时，六阶三叶像差占主导地位。还推断出，δ校正器中的六阶三叶像差通常比双六极校正器中的小。六阶三叶像差与有限量的四阶三叶像差和三倍像散相互抵消。在实验中，我们使用了一台配备用于探针和成像系统的δ校正器的低电压显微镜。分别使用龙奇图和衍射图谱来评估每个系统中的残余像差。应用平衡像差校正分别在60 kV和15 kV下获得了石墨烯和WS2样品的高分辨率透射电子显微镜图像。
