Tanaka N, Kimata H, Takashima T, Kizuka T
Department of Applied Physics, School of Engineering, Nagoya University, Japan.
Microsc Res Tech. 1998 Feb 15;40(4):265-76. doi: 10.1002/(SICI)1097-0029(19980215)40:4<265::AID-JEMT3>3.0.CO;2-R.
Tungsten single atoms and clusters composed of four and five atoms deposited on MgO (001) thin films were observed by high-resolution transmission electron microscopy at R.T. The observation was realized by optimizing the thickness of the MgO films and by using special imaging techniques such as an off-Bragg HREM method. The multislice simulation for the interpretation of the image contrast showed a possibility of discrimination of the atomic configuration of clusters, such as "b.c.c.," "on-top," or "f.c.c." type clusters, from details of the image-contrast. The image intensity at the center of the clusters with the b.c.c. configuration was evidently smaller than that of the clusters with the f.c.c. configuration. The reason for the difference was clarified through the multislice image simulation, suggesting that the lattice mismatch between the clusters and the MgO lattice was a key factor in determining the intensity of the center of the clusters.
在室温下，通过高分辨率透射电子显微镜观察了沉积在MgO(001)薄膜上的钨单原子以及由四个和五个原子组成的团簇。通过优化MgO薄膜的厚度并使用特殊成像技术（如非布拉格高分辨电子显微镜方法）实现了该观察。用于解释图像对比度的多切片模拟表明，从图像对比度细节中可以区分团簇的原子构型，如“体心立方”、“顶位”或“面心立方”型团簇。体心立方构型团簇中心的图像强度明显小于面心立方构型团簇的图像强度。通过多切片图像模拟阐明了这种差异的原因，表明团簇与MgO晶格之间的晶格失配是决定团簇中心强度的关键因素。
