Figure 3: van der Waals force detection.
From: Van der Waals interactions and the limits of isolated atom models at interfaces
(a) STM topography of the Cu-coordinated 3deh-DPDI network after measuring interaction curves above Ar, Kr and Xe atoms. (b) Frequency shift curves taken at the equivalent node sites with and without a Xe atom, measured with a Xe-functionalized tip. (c) Subtracted distance-dependence curves of the frequency shift for Ar–Xe, Kr–Xe and Xe–Xe junctions. (d) F4 interaction forces and Lennard-Jones fits for each system, extracted from the frequency shift signal and (e) the equivalent potential energy curves. Measurement parameters: Vtip=500 mV and I=4 pA in a, and A=38 pm, f=23,063 Hz and Q=52,044, and V=1 mV in b,c. Scale bar, 2 nm.
