An extreme ultraviolet 2e-ARPES setup based on dual time-of-flight analyzers

Abstract

Measuring the momentum and energy distribution of photoemitted correlated electron pairs is a promising approach to directly probe the nature of electron–electron interactions in quantum materials. In this work, we present a two electron angle resolved photoemission spectroscopy (2e-ARPES) setup based on two time-of-flight (TOF) analyzers and a gas fiber high-harmonic generation (HHG) extreme ultraviolet (XUV) source. For each incident XUV pulse, the system is capable of recording six-dimensional coincidence datasets (kinetic energy and two orthogonal momenta for each electron) with an unprecedented double photoemission energy resolution of $<$ 25 meV. The two TOF analyzers permit measurements of correlated electron pairs with momentum separation of $\sim 2{\text{Å}}^{-1}$. The performance of the setup is demonstrated by both single and double photoemission measurements, with an emphasis on the coincidence acquisition electronics and data extraction procedure for isolating correlated pair emission.