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Cristina Africh - CNR IOM
15 Nov 2020

Atomic scale microscopy at video rate: FastSTM experiments for NFFA-Europe users

Scanning tunneling microscopy up to 100 frames per seconds allows imaging dynamical processes on surfaces at the atomic scale
Click for full size image. Frames from FastSTM movie at 60 fps showing molecular self-assembly. © 2019 Elsevier B.V. All rights reserved.

Time resolution is a severe limitation in scanning probe microscopy (SPM), as the typical acquisition time for a single image is in the order of several seconds or even few minutes. The characterization of dynamical processes occurring at surfaces thus cannot be thoroughly addressed by conventional SPM.

To overcome this limitation, in the frame of NFFA-Europe joint research activities, we developed the FAST module, an add-on instrument capable of driving a commercial SPM at and beyond video rate frequencies. Recently, FAST has been made available to NFFA-Europe users for selected STM experiments and it has been already successfully employed during user access.

The novelty of this module is that it requires no modification of the existing scanner hardware and electronics, and its operation is totally transparent, allowing the user to switch immediately and seamlessly to the fast scanning mode when imaging in the conventional slow mode. The LabVIEW software package used for its control provides a user friendly, simple yet comprehensive interface, while the acquired movies are processed and converted into common video and image formats by a custom Python software package.

"This instrument can be of large interest to many of the research groups around the world that use SPM on a daily basis, with the added advantage of giving access to unprecedented time resolution in the imaging of dynamical processes on surfaces at the atomic scale"

Before opening the instrument to external users, we successfully tested this module driving commercial scanning tunneling microscope (STM) systems (Omicron VT-STM and LT-STM, SPECS Aarhus) in a quasi-constant height mode up to frame rates of 100 Hz and above, in a temperature range between 77 K and 600 K. It demonstrated extreme stability and high resolution imaging capabilities” says Mirco Panighel, one of the main developers at CNR-IOM.

During my user access at CNR-IOM, we synthesized polyhydrocarbon chains on Ni(111) and, thanks to FAST, I was capable of following the motion of these polymers on the surface in real time” says Laerte Patera, NFFA-Europe user in 2020.

As a proof of concept, the same module has also been used to drive a commercial AFM at ICN2, reaching frame rates up to 8 fps. This achievement shows that there is still potential to further develop FAST, making it of potential interest for an extremely large user community. 

This instrument can be of large interest to many of the research groups around the world that use SPM on a daily basis, with the added advantage of giving access to unprecedented time resolution in the imaging of dynamical processes on surfaces at the atomic scale” concludes Cristina Africh, responsible for the NFFA-Europe JRA task devoted to the development of FAST.

Publication Details

Ultramicr, Vol 205, pp 49-56 https://doi.org/10.1016/j.ultramic.2019.05.010

The new FAST module: A portable and transparent add-on module for time-resolved investigations with commercial scanning probe microscopes

Carlo Dri, Mirco Panighel, Daniel Tiemann, Laerte L.Patera, Giulia Troianode, Yves Fukamori, Fabian Knoller, Barbara A.J. Lechner, Giuseppe Cautero, Dario Giuressi, Giovanni Comelli, Jordi Fraxedas, Cristina Africh, Friedrich Esch

NFFA-Europe Facilities and Techniques

Video-rate STM experiments were performed in the STM laboratory of CNR-IOM thanks to FAST, the Fast-scan module developed by CNR-IOM, TUM and ICN2, as Joint Research Activity in the frame of the NFFA-Europe project. FAST is an add-on module applicable to commercial STMs and AFMs and capable to increase the conventional frame rate by several orders of magnitudes. FAST is available to NFFA-Europe users for selected STM experiments as part of the Structural & Morphological Characterisation Installation at CNR.

For more info

Mirco Panighel panighel@iom.cnr.it 

Cristina Africh africh@iom.cnr.it 

CNR-IOM, S.S. 14 km 163,5 - 34149 Trieste (Italy)