SKM 2023 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 75: Focus Session: Ultrafast Dynamics in Nanostructures I
O 75.6: Vortrag
Donnerstag, 30. März 2023, 12:15–12:30, GER 38
Probing hot electron dynamics in a metal nanotip with THz-STM — •Vivien Sleziona1, Faruk Krecinic1, Natalia Martín Sabanés1,2, Fabian Schulz1,3, Takashi Kumagai1,4, Martin Wolf1, and Melanie Müller1 — 1Fritz-Haber Institute, Berlin — 2IMDEA Nanoscience, 28049 Madrid, Spain — 3CIC NanoGUNE, San Sebastian, Spain — 4Institute of Molecular Science, 444-8585 Okazaki, Japan
In metal nanostructures, such as the tip of a scanning tunneling microscope (STM), the excitation and dynamics of hot electrons can differ significantly from their behavior in bulk solids. However, how exactly the electrons in an STM tip respond to femtosecond (fs) laser excitation is still poorly understood, although this is important for optimizing and understanding fs-laser-excited STM operation. Here we use a THz-gated STM to study the ultrafast dynamics of photoexcited electrons in a tungsten STM tip [1]. Specifically, we investigate the role of thermalized hot electrons for the generation of ultrafast photocurrents and tunneling in STM. Knowledge of the THz voltage transient combined with simulation of the electron dynamics inside the confined volume of the STM tip allows us to extract the electronic temperature and its ultrafast decay. We evaluate the relevance for fs laser-excited STM and discuss how the tip geometry affects electronic heating on ultrafast time scales. [1] N. Martín Sabanés et al., ACS Nano 16, 9, 14479-14489 (2022)