Optimizing atomic resolution of force microscopy in ambient conditions

TL;DR

This paper demonstrates atomic resolution imaging of KBr(001) in ambient conditions using frequency-modulation AFM with a quartz tuning fork sensor, analyzing hydration layer effects on cantilever damping for optimal imaging.

Contribution

It introduces a method to achieve atomic resolution in ambient conditions by optimizing amplitude and analyzing hydration layer effects on damping.

Findings

Atomic resolution achieved in ambient conditions.

Hydration layer thickness affects cantilever damping.

Optimal amplitude determined for high-quality imaging.

Abstract

Ambient operation poses a challenge to AFM because in contrast to operation in vacuum or liquid environments, the cantilever dynamics change dramatically from oscillating in air to oscillating in a hydration layer when probing the sample. We demonstrate atomic resolution by imaging of the KBr(001) surface in ambient conditions by frequency-modulation atomic force microscopy with a cantilever based on a quartz tuning fork (qPlus sensor) and analyze both long- and short-range contributions to the damping. The thickness of the hydration layer increases with relative humidity, thus varying humidity enables us to study the in uence of the hydration layer thickness on cantilever damping. Starting with measurements of damping versus amplitude, we analyzed the signal and the noise characteristics at the atomic scale. We then determined the optimal amplitude which enabled us to acquire high-quality atomically resolved images.