time-resolved μARPES and TOF-PEEM setup (Teilfinanzierung)

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We propose a setup for time- and angle-resolved photoemission spectroscopy with "μm" -sized field of view in real space (tr-μARPES) and time-resolved photoemission electron microscopy (tr-PEEM). The setup will include a 100kHz laser amplifier, an optical parametric amplifier (OPA) with difference frequency generation (DFG) for the efficient generation of mid-infrared pump pulses, a source for the generation of (extreme) ultraviolet probe pulses, a TOF-PEEM chamber equipped with a time-of-flight photoemission electron microscope (also referred to as time-of-flight momentum microscope), a Helium-cooled sample microscopy stage, a sample preparation chamber, and a load lock. This setup will allow us to measure the non-equilibrium carrier dynamics both in real and reciprocal space and the transient band structure of various low-dimensional solids and two-dimensional heterostructures exposed to visible, infrared, as well as strong-field MIR pump pulses. The envisioned TOF-PEEM offers important advantages compared to more conventional hemispherical analyzers including (1) the possibility to take images both in real and reciprocal space where the whole photoemission horizon can be accessed in a single shot, and (2) the possibility to reduce the field of view of the TOF-PEEM in μARPES mode which will allow us to measure the band structure of small or inhomogeneous samples. The repetition rate of 100kHz will ensure excellent signal-to-noise ratios for reasonable integration times and mitigate space charge issues. Cryogenic temperature will allow us to access various symmetry-broken ground states. The setup will be used to investigate carrier dynamics in twisted van der Waals heterostructures as well as the transient band structure of different low-dimensional solids exposed to quasi-periodic MIR driving.