Hydrodynamic damping of tip oscillation in pulsed-force atomic force microscopy

摘要

Although proven a powerful technique for mapping adhesion and surface mechanical properties at high lateral resolution, pulsed-force (PF) atomic force microscopy (AFM) is problematic in liquid, due to heavy hydrodynamic damping of cantilever vibration. We present computer simulations using the simple harmonic oscillation model to explore the changes of deflection signal profile that occur from air to liquid environment. In agreement with experimental results, we find that oscillation phase lag plays a key role in the signal profile. When imaging in liquid, the deflection caused by liquid oscillation may exceed that caused by tip-sample contact repulsion and adhesion, which brings particular consideration for PF-AFM imaging in liquid.