Comment on 'Field ion microscopy characterized tips in noncontact atomic force microscopy: Quantification of long-range force interactions'

TL;DR

This paper critiques a previous study on noncontact atomic force microscopy, highlighting errors in tip radius measurement via field ion microscopy and providing guidance to improve future experimental accuracy.

Contribution

It identifies common errors in ring counting methods used for tip radius estimation in FIM, aiding more accurate future measurements.

Findings

Underestimation of tip radius in the cited study due to ring counting errors

Clarification of proper ring counting techniques in FIM

Guidance for reducing measurement errors in tip characterization

Abstract

A recent article by Falter et al. (Phys. Rev. B 87, 115412 (2013)) presents experimental results using field ion microscopy characterized tips in noncontact atomic force microscopy in order to characterize electrostatic and van der Waals long range forces. In the article, the tip radius was substantially underestimated at ~4.7 nm rather than ~8.1 nm due to subtleties in the application of the ring counting method. We point out where common errors in ring counting arise in order to benefit future experimental work in which the determination of tip radius by FIM is important.