Figure 2
From: Carbon-fiber tips for scanning probe microscopes and molecular electronics experiments
Carbon-fiber tip and substrate interaction. (a) Simultaneous measurement of force (black line, left axis) and tunnel current (red line, right axis) during a tip-sample approach. The inset shows the simultaneously measured quality factor of the tuning fork oscillation. (b) Topography image of an octanethiol self-assembled monolayer (SAM) on Au (111) sample obtained in the constant tunnel current STM mode and (c) the simultaneously measured frequency shift of the tuning fork oscillation which enables to unambiguously identify bare gold areas (dark) and SAM-covered regions (bright).