Abstract
Recent progress in laser-based high-repetition rate extreme ultraviolet (EUV) light sources and multidimensional photoelectron spectroscopy enables the build-up of a new generation of time-resolved photoemission experiments. Here, we present a setup for time-resolved momentum microscopy driven by a 1 MHz fs EUV table-top light source optimized for the generation of 26.5 eV photons. The setup provides simultaneous access to the temporal evolution of the photoelectron's kinetic energy and in-plane momentum. We discuss opportunities and limitations of our new experiment based on a series of static and time-resolved measurements on graphene.
Highlights
Full spectroscopic information on the electronic band structure of a solid-state material requires the measurement of multiple observables
It has been shown that the combination of the timeof-flight momentum microscopy with femtosecond pump-probe spectroscopy enables the collection of multidimensional datasets describing the ultrafast non-equilibrium dynamics of the material under strong illumination
We present the powerful combination of a tabletop high-harmonic generation (HHG) beamline driven by a fiber laser system, and a flexible pump beamline, all operating at the exceptional repetition rate of 1 MHz, with a momentum microscope endstation guaranteeing simultaneous detection of energy- and in-plane-momentumresolved photoemission data
Summary
Full spectroscopic information on the electronic band structure of a solid-state material requires the measurement of multiple observables. The large number of photoemitted electrons per pulse could lead to signal distortions due to space charge effects.38–41 Avoiding these has so far hindered satisfactory counting statistics at manageable measurement durations. Recent developments of the femtosecond laser technology and table-top HHG sources have made EUV sources operating at MHz-level repetition rates widely available, which are promising for time-resolved photoemission spectroscopy.. We present the powerful combination of a tabletop HHG beamline driven by a fiber laser system, and a flexible pump beamline, all operating at the exceptional repetition rate of 1 MHz, with a momentum microscope endstation guaranteeing simultaneous detection of energy- and in-plane-momentumresolved photoemission data. In a time-resolved optical-pump— EUV-probe configuration the femtosecond time evolution of the non-equilibrium charge carrier and band renormalization dynamics can be followed with unprecedented information depth in the full Brillouin zone. We will demonstrate the capabilities of this novel system based on exemplary measurements on the monolayer graphene
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