Force microscope provides atomically resolved images of surfaces immersed in a liquid. The presence of different chemical species in the interface (cations, anions, water, neutral atoms) complicates the adscription of the observed features to a given species. We develop a 3D atomic force microscopy method to identify the cations adsorbed on a mica surface from a potassium chloride solution. The method is based on measuring the peak value of the attractive force within the Stern layer. The maximum of the attractive force shows site-specific variations. The positions with the highest attractive force values are associated with the presence of adsorbed potassium ions, while the other positions are associated with a local depletion of the hydration layer. This criterion provides a surface coverage of K cations that is consistent with the one reported by other techniques.

中文翻译：

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通过3D力显微镜鉴定云母-液体界面上的单个吸附阳离子

力显微镜可提供原子分解的图像，并将其浸入液体中。界面（阳离子，阴离子，水，中性原子）中存在不同的化学物种，会使给定物种的观测特征更加复杂。我们开发了3D原子力显微镜方法，以确定从氯化钾溶液中吸附在云母表面的阳离子。该方法基于测量斯特恩层内的吸引力的峰值。吸引力的最大值显示了特定位置的变化。具有最高吸引力值的位置与吸附的钾离子的存在相关，而其他位置与水合层的局部消耗相关。