Fig. 3: Tip manipulation induced the adsorption configuration change of the oxalate anion on Cu(100) surface.

a STM images of the tetramer and constructed trimer, dimer and monomer (from the top to the bottom panels, highlighted by dashed yellow circles, STM set point: 100 mV, 50 pA. b–e Constant-height AFM images (\(\Delta f\)) (b), simulated AFM images (c) and the structural models (d, e) of the 4 K⁺ ∙ C₂O₄^2-, 3 K⁺ ∙ C₂O₄^2-, 2 K⁺ ∙ C₂O₄^2-, K⁺ ∙ C₂O₄^2- clusters (from the top to the bottom panels). K, Cu, C, O atoms are denoted by purple, yellow, grey and red spheres, respectively. The tip heights of (b) are 30 pm, 40 pm, 110 pm, 40 pm (from top to bottom), which are referenced to the STM set point on the Cu substrate (100 mV, 50 pA). The tip heights of c are 10.73 Å, 11.21 Å, 12.35 Å, 10.88 Å, which are defined as the vertical distance between the apex atom of the metal tip and the outermost atom of the Cu substrate. The black arrows denote the lower lying oxygen atoms in the 3 K⁺ ∙ C₂O₄^2- cluster. The green arrows denote the upward oxygen atoms in the 2 K⁺ ∙ C₂O₄^2- cluster.