Interaction imaging with amplitude-dependence force spectroscopy

TL;DR

This paper introduces amplitude-dependence force spectroscopy (ADFS), a novel method combining high accuracy force measurements with high resolution imaging in AFM to quantitatively map surface interactions.

Contribution

The paper presents ADFS, a new technique that enables simultaneous high-resolution imaging and quantitative measurement of tip-surface forces in AFM.

Findings

ADFS accurately measures conservative and dissipative forces.

It successfully maps nano-mechanical interactions on heterogeneous surfaces.

Compatible with commercial AFM systems.

Abstract

Knowledge of surface forces is the key to understanding a large number of processes in fields ranging from physics to material science and biology. The most common method to study surfaces is dynamic atomic force microscopy (AFM). Dynamic AFM has been enormously successful in imaging surface topography, even to atomic resolution, but the force between the AFM tip and the surface remains unknown during imaging. Here, we present a new approach that combines high accuracy force measurements and high resolution scanning. The method, called amplitude-dependence force spectroscopy (ADFS) is based on the amplitude-dependence of the cantilever's response near resonance and allows for separate determination of both conservative and dissipative tip-surface interactions. We use ADFS to quantitatively study and map the nano-mechanical interaction between the AFM tip and heterogeneous polymer surfaces. ADFS is compatible with commercial atomic force microscopes and we anticipate its wide-spread use in taking AFM toward quantitative microscopy.