In-situ characterization of contamination within an Atomic Force Microscope tip-sample system

TL;DR

This paper presents a method using AFM imaging and spectroscopy to characterize contamination in tip-sample systems, revealing contamination levels and their impact on measurements in ambient conditions.

Contribution

It introduces an in-situ AFM-based approach to assess contamination in tip-sample systems, linking contamination to changes in the Hamaker constant.

Findings

AFM cantilevers are often severely contaminated after long-term storage.

Spectroscopy data can determine the Hamaker constant, which varies with contamination.

The method enables contamination assessment without additional equipment.

Abstract

Atomic force microscopy is based on tip sample interaction, which is determined by the properties of tip and sample. Unfortunately, in particular in ambient conditions the tip as well as the sample are contaminated, and it is not clear how this contamination may affect data in Atomic Force Microscopy (AFM) applications. In the present work we propose to use on the one hand AFM imaging of the cantilever chips and on the other hand multidimensional AFM spectroscopy techniques to characterize the state of contamination of the tip sample system. We find that typically AFM cantilevers may be severely contaminated when taken from typical packaging boxes that have been opened for a long time. In addition, by acquisition spectroscopy data as a function of tip-sample voltage and tip-sample distance, we are able to determine the Hamaker constant of the system, which depends strongly on the contamination within the tip-sample system. This method allows for in-situ characterization of the tip-sample system using only AFM techniques.