Deployment of an integrated fast scanning probe microscopy module—control software and performance

Scanning probe microscopes (SPMs) give a unique atomic-scale insight into surface dynamics in different environments. To access fast dynamics, we have recently presented a FastSPM add-on module based on a new generation field-programmable gate array, which makes fast lateral control and signal measurement accessible to virtually any commercial SPM. This module integrates various measurement modes with different temporal and spatial resolution, enables a seamless transition, and is user-friendly, while working at the limits of mechanical stability of an SPM. Here, we report on the performance of this module in three specific measurement modes in concrete examples: (i) quasi-constant height image acquisition with a time resolution down to at least 100 ms/frame; (ii) tracking single features such as adatoms, vacancies, adsorbates or nanoparticles under full lateral and vertical feedback to investigate diffusion, isomerization or reaction events with a time resolution down to 500 μs; and (iii) high-speed measurements above specific surface features, in which signal fluctuations, e.g. due to catalytic reaction cycles, can be detected with a time resolution down to 1 μs. We illustrate the transition between movie acquisition and tracking on the example of a small oxide-supported metal cluster and demonstrate sub-Å tracking precision. Furthermore, we test the frequency up to which external mechanical excitations can be followed by high-speed measurements. Finally, we demonstrate the stability of drift-corrected movie acquisition and high-speed measurements on porphyrin monolayers under full electrochemical control. In this system, we see the intermediate formation of short-lived phosphate overlayers and monitor the modulation of tunneling current noise upon a catalytic reaction. On top of these standard modes, we further present a range of convenient tools for resonance frequency characterization of the instrument, tip positioning, test pattern movements, lateral feedback optimization and acquisition of slow reference images.