An open-source, end-to-end workflow for multidimensional photoemission spectroscopy

Abstract

Characterization of the electronic band structure of solid state materials is routinely performed using photoemission spectroscopy. Recent advancements in short-wavelength light sources and electron detectors give rise to multidimensional photoemission spectroscopy, which permits parallel measurements of the electron spectral function in energy, two momentum components and additional physical parameters with single-event detection capability. Processing the photoelectron event streams with a rate of a few to tens of megabytes per second poses a major data challenge in the field. We describe an opensource, distributed workflow for efficient interaction with single-electron events in photoemission band mapping experiments compatible with beamlines at 3 rd and 4 th generation light sources as well as table-top laser sources. The workflow transforms single-event data into calibrated and structured formats for subsequent storage, visualization and further analysis by facility users. The workflow can be archived for reuse and provides a basis for the documentation and comparison of multidimensional band mapping data and their integration into materials science databases.

A quantitative comparison of time-of-flight momentum microscopes and hemispherical analyzers for time- and angle-resolved photoemission spectroscopy experiments

“…Secondly, a flat and isotropic sample holder is required to prevent distortions of the extractor fields. Thirdly, acquisition with the MM requires processing and storage of large data sets (∼ 100 GB for a typical data set of 10 10 events), and involves complex data binning and analysis procedures 42 . Determination of the complete (time-resolved) electronic band structure dynamics with the MM bears an enormous potential.…”

“…Each registered event directly corresponds to a single photoelectron. Saving this data stream at a single-event level permits event-wise correction and calibration, and selective binning later during analysis 37,42 . The operating principle of the DLD limits the count rate to a single electron per pulse 43,44 , resulting in maximum rates of ∼ 5 × 10 5 cts/s, corresponding to the repetition rate of the laser system.…”

Time-resolved momentum microscopy with a 1 MHz high-harmonic extreme ultraviolet beamline

“…This is achieved using a set of stretching and shearing matrices which optimize the known hexagonal symmetry of the Dirac points. 63 We have also rotated the data such that a high symmetry axis of the band structure lies along the k x axis. The distortion-corrected band structure agrees well with the band structure predicted by a tight-binding calculation.…”

Ultrafast Dynamical Lifshitz Transition

“…Concerning the data post-processing, the combination of the high repetition rate of our beamline and the multidimensional data recording scheme 11 leads to typical datasets involving 10 9 -10 11 detected events and a typical dataset size of few hundreds of gigabytes (GBs). We thus use a recently developed open-source workflow 31 to efficiently convert these raw single-event-based datasets into binned calibrated data hypervolumes of the desired dimension, including axes calibration and detector artifact corrections. Binning of the single-event data to a specific hypervolume reduces the data to a manageable size of a few to tens of gigabytes.…”