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

Abstract 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 (FPGA), 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. Weillustrate 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-speedmeasurements. 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.