Dresden 2020 – scientific programme

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O: Fachverband Oberflächenphysik

O 28: Poster Session - Scanning Probe techniques: Method Development

O 28.8: Poster

Monday, March 16, 2020, 18:15–20:00, P1A

How to Resolve Dynamic Surface Processes by High-Speed Scanning Tunneling Microscopy — •Zechao Yang, Leonard Gura, Jens Hartmann, Heinz Junkes, William Kirstädter, Patrik Marschalik, Markus Heyde, and Hans-Joachim Freund — Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin, Germany

Here we present the concept of a new high-speed scanning tunneling microscope (STM) for resolving dynamic processes in amorphous network structures at the atomic scale.

The design of the microscope body is compact, rigid, and highly symmetric to ensure vibrational stability and low drift characteristics. The scanner unit in this microscope consists of two independent tube piezos for slow and fast scanning, respectively. A commercial scanning probe microscopy (SPM) controller is used for the slow scanner unit, while a high-speed Versa Module Eurocard bus (VMEbus) system controls the fast scanning. The data acquisition of the tunneling signal, x-, y-, and z-position is realized by a high-speed digitizer. Scan control and data acquisition has been programmed in an EPICS framework.

Another important feature in our approach is the implementation of a spiral scan option for avoiding internal resonance frequencies of the microscope body. The tip scans in a quasi-constant height mode, where the logarithm of the tunneling current signal can be regarded as roughly proportional to the surface topography.

In first test measurements at room temperature, diffusion processes within an O(2x2) coverage on Ru(0001) have been atomically resolved with a time resolution of 25 milliseconds per frame.