The foremost atom of the tip in a scanning probe microscope is critically important for precise imaging results. In atomic force microscopy, the front atom significantly affects atomic-scale contrast and atom manipulation. The chemical species is a dominant factor in determining the tip state, and in situ chemical identification of a tip apex remains a challenging task. Researchers found that Pauling's equation is applicable to the analysis of tip apex atoms. The team also demonstrated a way to determine electronegativity of surface atoms solely by experiments.
