Sumaiya Saima A, Liu Jun, Baykara Mehmet Z
Department of Mechanical Engineering, University of California Merced, Merced, California95343United States.
ACS Nano. 2022 Dec 27;16(12):20086-20093. doi: 10.1021/acsnano.2c08321. Epub 2022 Oct 25.
A great number of chemical and mechanical phenomena, ranging from catalysis to friction, are dictated by the atomic-scale structure and properties of material surfaces. Yet, the principal tools utilized to characterize surfaces at the atomic level rely on strict environmental conditions such as ultrahigh vacuum and low temperature. Results obtained under such well-controlled, pristine conditions bear little relevance to the great majority of processes and applications that often occur under ambient conditions. Here, we report atomic-resolution surface imaging via conductive atomic force microscopy (C-AFM) under ambient conditions, performed at high scanning speeds. Our approach delivers atomic-resolution maps on a variety of material surfaces that comprise defects including single atomic vacancies. We hypothesize that atomic resolution can be enabled by either a confined, electrically conductive pathway or an individual, atomically sharp asperity at the tip-sample contact. Using our method, we report the capability of charge state manipulation of defects on MoS and the observation of an exotic electronic effect: room-temperature charge ordering in a thin transition metal carbide (TMC) crystal (i.e., an MXene), α-MoC. Our findings demonstrate that C-AFM can be utilized as a powerful tool for atomic-resolution imaging and manipulation of surface structure and electronics under ambient conditions, with wide-ranging applicability.
从催化到摩擦，大量的化学和力学现象都由材料表面的原子尺度结构和性质所决定。然而，用于在原子水平表征表面的主要工具依赖于诸如超高真空和低温等严格的环境条件。在这种严格控制的原始条件下获得的结果与大多数通常在环境条件下发生的过程和应用几乎没有关联。在此，我们报告了在环境条件下通过导电原子力显微镜（C-AFM）以高扫描速度进行的原子分辨率表面成像。我们的方法在包括单原子空位等缺陷的各种材料表面上提供原子分辨率图谱。我们推测，原子分辨率可以通过受限的导电通道或尖端-样品接触处单个原子尖锐的凸起实现。使用我们的方法，我们报告了对MoS上缺陷的电荷态进行操纵的能力以及对一种奇特电子效应的观察：在薄过渡金属碳化物（TMC）晶体（即MXene）α-MoC中的室温电荷有序化。我们的研究结果表明，C-AFM可作为一种强大的工具，用于在环境条件下对表面结构和电子学进行原子分辨率成像和操纵，具有广泛的适用性。
