Dynamics of Correlated Materials
Emmy Noether Group Laurenz Rettig
Dynamics of Correlated Materials
Emmy Noether Group Laurenz Rettig
Dynamics of Correlated Materials
Emmy Noether Group Laurenz Rettig

News Post
A quantitative comparison of time-of-flight momentum microscopes and hemispherical analyzers for time-resolved ARPES experiments
Dec 2020

Recent advancements in time-of-flight-based momentum microscope development have led to a growing presence of this novel detection scheme in photoemission studies, as it enables highly parallelized and simultaneous acquisition of the full 3-dimensional momentum- and energy-resolved photoelectron distribution. Combining such instruments with modern high-repetition-rate extreme ultraviolet (XUV) laser sources for ultrafast pump-probe photoemission experiments seems like an ideal match, and is followed by several groups worldwide. However, particularly important for time-resolved studies, several factors such as space-charge effects need to be considered and depend on the chosen analyzer type.

In our study (Rev. Sci. Instr. 91, 123112 (2020)) we present a first benchmark comparison of the momentum microscope and the current standard spectrometer used in photoelectron spectroscopy, i.e., the hemispherical analyzer, with a focus on time-resolved ARPES experiments. Our unique setup combines a state-of-the-art laser-based high-repetition-rate XUV light source and both types of photoelectron detectors in a single apparatus, which allows us to quantify critical experimental parameters. We identify advantages and limitations of both instruments, and discuss their complementary nature in the context of various (time-resolved) ARPES scenarios.

Temporal evolution of the excited state signal in
WSe2 acquired with the momentum microscope (iso-energy contour
at 1.6 eV) and the hemispherical analyzer (along ő£ – K)