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O: Fachverband Oberflächenphysik

O 80: Poster: Scanning Probe Techniques - Method Development

O 80.18: Poster

Mittwoch, 14. März 2018, 18:15–20:30, Poster A

Development of an ultrafast THz-gated Scanning tunneling microscope combined with optical photoexcitation — •Natalia Martín Sabanés, Mellanie Müller, and Martin Wolf — Fritz Haber Institute, Berlin, Germany

Unravelling the complex spatio-temporal dynamics of nanostructures and molecules is essential to optimize a variety of applications in nanoelectronics or energy conversion devices. Focusing THz-pulses into the junction of a scanning tunneling microscope (STM) modulates the bias on ps to fs time scales, providing ultrafast control of the tunneling current. THz-gated STM has been successfully used to monitor ultrafast processes on atomic length scales employing a THz pump-THz probe excitation scheme.[1] Despite the outstanding capabilities that this scheme holds for the study of ultrafast phenomena on the atomic level, different experimental configurations allowing the use of optical photoexcitation remain unexplored. We introduce the technical development of an ambient THz-gated STM combined with near-field optical photoexcitation. We discuss the suitability of different THz emitters as well as the use of plasmonic nanofocusing on nanostructured gold tips to increase photoexcitation efficiency and to reduce the thermal load of the tunneling junction.[2] Combining the atomic spatial and fs temporal resolution of a THz-gated STM with optical photoexcitation will provide access to a broader range of spatio-temporal phenomena.

[1] Nature Photonics, 2013, 7(8), 620-625. Nature,2016 539(7628), 263-267. Nature Physics, 2017, 13(6), 591-598. [2] ACS Photonics, 2016, 3(4), 611-619.