IFW Dresden, Institute for Metallic Materials, P.O. Box 270116, D-01171 Dresden, Germany.
Nano Lett. 2012 Dec 12;12(12):6071-7. doi: 10.1021/nl302280x. Epub 2012 Nov 13.
We present a method that allows for a quantitative measurement of the surface self-diffusion on nanostructures, such as nanoparticles, at the atomic scale using aberration-corrected high-resolution transmission electron microscopy (HRTEM). The diffusion coefficient can be estimated by measuring the fluctuation of the atom column occupation at the surface of Au nanoparticles, which is directly observable in temporal sequences of HRTEM images. Both a Au icosahedron and a truncated Au octahedron are investigated, and their diffusion coefficients are found to be in the same order of magnitude, D = 10(-17) to 10(-16) cm(2)/s. It is to be assumed that the measured surface diffusion is affected by the imaging electron beam. This assumption is supported by the observed instability of a (5 × 1) surface reconstruction on a {100} Au facet.
我们提出了一种方法，使用经过像差校正的高分辨率透射电子显微镜（HRTEM），可以在原子尺度上对纳米结构（如纳米粒子）的表面自扩散进行定量测量。通过测量 Au 纳米粒子表面原子列占据的涨落，可以估计扩散系数，这在 HRTEM 图像的时间序列中是直接可见的。我们研究了一个 Au 二十面体和一个截断的 Au 八面体，发现它们的扩散系数处于相同的数量级，D = 10(-17) 到 10(-16) cm(2)/s。可以假设测量到的表面扩散受到成像电子束的影响。这一假设得到了在 Au{100}面的（5 × 1）表面重构上观察到的不稳定性的支持。
