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O: Fachverband Oberflächenphysik

O 2: Scanning probe techniques: Method development I

O 2.6: Vortrag

Montag, 12. März 2018, 11:45–12:00, MA 004

Resolving Dynamic Processes in Real Space with Variable-Temperature High-Speed Scanning Tunneling Microscopy — •Leonard Gura, Zechao Yang, Patrik Marschalik, Heinz Junkes, Markus Heyde, and Hans-Joachim Freund — Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin, Germany

Scanning Tunneling Microscopy (STM) atomically resolved 2D-silica in both, the amorphous [1] and the crystalline state, leading to a structural comparison of the two phases [2]. Resolving dynamic changes in 2D network structures can give indications for the fundamental processes at the atomic scale occurring during glass-transformation.

With the scope of monitoring dynamic processes during the temperature induced change of the network structure, we design a variable temperature high-speed STM. A temperature ramp from 4 to 1500 K is enabled by a continuous-flow cryostat and a sample stage heated by electron bombardment. Thermal drift is reduced due to the symmetric setup of the microscope. For higher frame rates, a spiral scan geometry will be applied, which represents a monotonic continuous function of the angle for the radius without points of inflection nor crossing of lines. The scan is realized with a combination of a conventional STM control unit and custom made high-speed electronics. Due to the high data throughput, programs are needed, which automatically detect atom and ring-center positions in the recorded STM images.

We hope to clarify important structural steps in oxide network structures at so far with STM unrivaled time scales.

[1] DOI: 10.1002/anie.201107097 [2] DOI: 10.1021/jp3062866