This article introduces the application of carbon nanotube tips in MAC mode AFM measurements in liquids. Carbon nanotube tips, with sharp geometry, intrinsic electrical conductivity, and mechanical resilience, offer a solution to the common tip-wear problem and have been successfully demonstrated in lithographic oxidation of hydrogen-passivated silicon surfaces.
This document describes the application of carbon nanotubes as tips for Atomic Force Microscopy (AFM) to address issues like tip wear and inconsistent geometry. It highlights the advantages of using these tips in Magnetic AC Mode (MAC Mode) for measurements in liquids, such as minimizing acoustic vibration and improving signal-to-noise ratios.
The note details experimental results where carbon nanotube tips were used to image surfaces in water solutions, including mica and gold films, as well as plasmid DNA molecules. It discusses the mechanical properties of the nanotubes, their buckling behavior under force, and the resulting high-resolution imaging capabilities compared to standard tips.
They provide a well-defined atomic configuration at the tip end to study tip-sample interactions and measure single-molecular bond-rupture forces directly from force-distance curves.
It minimizes disturbance by directly driving the AFM cantilever with an oscillating magnetic field, which reduces background resonances from the cantilever holder and fluid body.
The cantilever was driven at a frequency of about 30 kHz by a solenoid under the sample plate.