961239.fig.004a
(a) Hemispherical tip
961239.fig.004b
(b) Conical tip
961239.fig.004c
(c) AFM (hemispherical tip)
961239.fig.004d
(d) AFM (conical tip)
961239.fig.004e
(e) STM (hemispherical tip)
961239.fig.004f
(f) STM (conical tip)
Figure 4: (a, b) Atomic structures of hemispherical and conical (aspect ratio = 1) 110-oriented 𝑊 tips (radius 3 nm, lowest 5 atomic layers shown) scanning over a raised atom on a flat plane. Interatomic distances are to scale (sample atomic spacing = 2.5 Å); for clarity, tip-sample separation is larger than used in calculations and atoms are shown smaller than their derived radii. (c, d) Topographical images produced by simulated imaging of sample atom and surface in AFM mode by hemispherical and conical tips (setpoint defined as point of maximum attractive force). (e, f) Topographical images produced by simulated imaging of sample atom and surface in constant-current STM mode (same setpoint) by hemispherical and conical tips. Scanned area: 2 0 × 2 0  Å2.