论文标题
成像单层MOS2中的电子电荷密度在Ångstrom量表
Imaging the electron charge density in monolayer MoS2 at the Ångstrom scale
论文作者
论文摘要
四维扫描透射电子显微镜（4D-STEM）最近因其具有子-Oungstrom空间分辨率的原子电场的能力而受到广泛关注。这些电场图代表了核，核心电子和价电子的综合作用，分离它们的贡献是不平凡的。在本文中，我们同时使用了4D型质量中心（COM）图像和环形暗场（ADF）图像来确定单层MOS2中的电子电荷密度。我们发现核心电子和价电子都有助于衍生的电子电荷密度。但是，由于探针形状的模糊，价电子贡献几乎形成了几乎无特征的背景，而大多数空间调制都来自核心电子。我们的发现突出了探针形状在解释4D茎中得出的电荷密度方面的重要性。
Four-dimensional scanning transmission electron microscopy (4D-STEM) has recently gained widespread attention for its ability to image atomic electric fields with sub-Ångstrom spatial resolution. These electric field maps represent the integrated effect of the nucleus, core electrons and valence electrons, and separating their contributions is non-trivial. In this paper, we utilized simultaneously acquired 4D-STEM center of mass (CoM) images and annular dark field (ADF) images to determine the electron charge density in monolayer MoS2. We find that both the core electrons and the valence electrons contribute to the derived electron charge density. However, due to blurring by the probe shape, the valence electron contribution forms a nearly featureless background while most of the spatial modulation comes from the core electrons. Our findings highlight the importance of probe shape in interpreting charge densities derived from 4D STEM.
