We are interested in the spatio-temporal response of solid state surfaces, nanostructures, and molecules following ultrafast laser 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 on ultrashort length und ultrafast time scales.

To achieve this goal, we are putting efforts into the development of ultrafast scanning probe methods, with a strong focus on broadband THz-gated STM combined with femtosecond optical excitation and all-optical plasmon-assisted femtosecond STM. For more information please check our research page and follow our news below.

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In close collaboration with Akitoshi Shiotari, we are pleased to present our recent work on the use of non-contact AFM for optical near-field imaging of surfaces using stable plasmonic picocavities in a cryogenic ultra-high vacuum environment. By illuminating a plasmonic tip attached to a quartz tuning fork sensor oscillating at tapping amplitudes of 1 nm or less, we are able to record light scattering from the extremely small picocavity volume with high sensitivity. The use of focused ion beam polished silver tips ensures strong and highly localised field enhancement with minimal background scatter. This allows us to obtain a reproducible material contrast image of monolayer silicon islands on a silver surface with 1 nm lateral resolution. Thanks for the great cooperation! Preprint available here: https://arxiv.org/abs/2410.18455

The European Research Council has awarded Melanie an ERC Starting Grant for her project FASTOMIC. With a total amount of €1.5 million for a period of five years, this grant will allow us to push the limits of ultrafast microscopy to study the emergence and dynamics of nonequilibrium quantum states in real time and space. Many thanks to the Ultrafast STM team and many collaborators for the great support!

Our results on the rotating spintronic terahertz emitter are now published in APL. If you are interested in using the STE with a high-power femtosecond laser system, take a look! It survives excitation at 18 W at 1 MHz focused on a pump spot only a few millimeters in size. Best of all: The concept is scalable, inexpensive, and comparatively compact. See here for more details: Vaitsi et al., Appl. Phys. Lett. 125, 071107 (2024)

Sophie is doing her Masters in chemistry at the Freie Universität Berlin and is joining us for a three-month internship. She will help with the installation of new sample preparation equipment, perform maintenance on the THz-STM and gain some experience with ultrafast STM. Welcome Sophie!