Yamashita Shunsuke, Koshiya Shogo, Ishizuka Kazuo, Kimoto Koji
Surface Physics and Structure Unit, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan Department of Applied Chemistry, Kyushu University, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
Surface Physics and Structure Unit, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan.
Microscopy (Oxf). 2015 Apr;64(2):143-50. doi: 10.1093/jmicro/dfu115. Epub 2015 Jan 30.
A quantification procedure for annular dark-field (ADF) imaging, in which a quantitative contrast is given as a scattering intensity normalized by an incident probe current, is presented. The obtained ADF images are converted to quantitative ADF images using an empirical equation, which is a function of an ADF imaging system setting. The quantification procedure fully implements the nonlinear response of the ADF imaging system, which is critical in high-sensitivity observation. We applied the procedure for observation of a graphene specimen with 1-4 layers. The inner and outer angles of an ADF detector, which are important parameters in quantitative analyses, were precisely measured. The quantitative contrast of ADF images was in agreement with that of simulated images, and the quantitative ADF imaging allowed us to directly count the number of graphene layers.
本文提出了一种环形暗场（ADF）成像的量化方法，其中定量对比度表示为散射强度除以入射探针电流。利用一个经验公式将获得的ADF图像转换为定量ADF图像，该经验公式是ADF成像系统设置的函数。该量化方法充分考虑了ADF成像系统的非线性响应，这在高灵敏度观测中至关重要。我们将该方法应用于1-4层石墨烯样品的观测。精确测量了ADF探测器的内角和外角，这是定量分析中的重要参数。ADF图像的定量对比度与模拟图像相符，定量ADF成像使我们能够直接计算石墨烯层数。
