We are interested in the spatio-temporal response of solid state surfaces, quantum materials, and nanostructures following ultrafast optical or electronic excitation. Our goal is to obtain an atomistic understanding of photoinduced processes on (sub-) nanometer length and femtosecond time scales by employing novel pump-probe schemes for ultrafast scanning probe microscopy (SPM). We envision to study, drive and control solid state matter in highly non-equilibrium states and probe its dynamics locally at atomic scales.

To achieve this goal, we are putting efforts into the development of ultrafast scanning probe methods, with a focus on broadband THz-gated STM combined with femtosecond optical excitation and optical photon-assisted femtosecond STM. Besides detecting the localized tunneling signals, we complement our methodological approach by local light detection and optical near-field techniques. For detailed information and updates, please follow our news below.

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Since September we are happy to welcome Henrik as a new member of the light-driven STM team. Henrik is a master student from the Freie Universität Berlin with interest in physical chemistry. In his master project he will explore the light-matter interaction of ultrathin semiconductor films inside plasmonic nanojunctions with STM. Welcome Henrik!

Is hot electron tunneling from a femtosecond laser-excited STM tip thermal or nonthermal? (How) do the femtosecond dynamics of hot electrons inside the tip affect the ultrafast photocurrent response in STM? We have addressed this fundamental question using a THz-gated STM and are pleased that our results are now being published in ACS Nano. (DOI: 10.1021/acsnano.2c04846)

We had a closer look into the nonequilibrium dynamics of hot electrons inside
a photoexcited STM tip, and were curious about the question: does the tunneling of photo-generated hot electrons in STM have thermal or nonthermal character? THz sampling inside the photoexcited STM junction can answer this question, have a closer look at our preprint: https://doi.org/10.48550/arXiv.2205.08248.