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Momentum microscopy with combined hemispherical and time-of-flight electron analyzers at the soft X-ray beamline I09 of the diamond light source

At a Glance

Section titled ā€œAt a Glanceā€
MetadataDetails
Publication Date2025-05-20
JournalUltramicroscopy
AuthorsMatthias Schmitt, Deepnarayan Biswas, Olena Tkach, O. Fedchenko, Jieyi Liu
InstitutionsDiamond Light Source, University of WĆ¼rzburg
Citations2

Abstract

Section titled ā€œAbstractā€

The three-dimensional recording scheme of time-of-flight momentum microscopes (ToF-MMs) is advantageous for fast mapping of the photoelectron distribution in (E,k) parameter space over the entire Brillouin zone. However, the 2 ns pulse period of most synchrotrons is too short for pure ToF photoelectron spectroscopy. The use of a hemispherical analyzer (HSA) as a pre-filter allows ToF-MM at such high pulse rates. The first HSA & ToF hybrid MM is operated at the soft X-ray branch of beamline I09 at the Diamond Light Source, UK. The photon energy ranges from 105 eV to 2 keV, with circular polarization available for hĪ½ ā‰„ 145 eV. The HSA reduces the transmitted energy band to typically 0.5 eV, which is then further analyzed by ToF recording. In initial experiments, the overall efficiency gain when switching from the standard 2D (k<sub>x</sub>,k<sub>y</sub>) mode to the 3D (k<sub>x</sub>,k<sub>y</sub>,E<sub>kin</sub>) hybrid mode was about 24. This value is determined by the number of resolved kinetic energies (here 12) and the transmission gain of the electron optics due to the high pass energy of the HSA in hybrid mode (E<sub>pass</sub> up to 500 eV). The transmission gain depends on the size of the photon footprint on the sample. Under k-imaging conditions, the energy and momentum resolution are 10.2 meV (FWHM) (4.2 meV with 200 Ī¼m slits and E<sub>pass</sub> = 8 eV) and 0.010 ƅ<sup>-1</sup>. The energy filtered X-PEEM mode showed a spatial resolution of 250 nm. As examples, we show 2D band mapping of bilayer graphene, 3D mapping of the Fermi surface of Cu, circular dichroic ARPES for intercalated indenene layers, and the sp valence band of Au. Full-field photoelectron diffraction patterns of Ge show rich structure in k-field diameters of up to 6 ƅ<sup>-1</sup>.

Tech Support

Section titled ā€œTech Supportā€

Original Source

Section titled ā€œOriginal Sourceā€

References

Section titled ā€œReferencesā€
  1. 2024 - Low-energy spin-polarized electrons: their role in surface physics [Crossref]
  2. 2022 - Spin- and time-resolved photoelectron spectroscopy and diffraction studies using time-of-flight momentum microscopes [Crossref]
  3. 2008 - Development of a momentum microscope for time resolved band structure imaging [Crossref]
  4. 2015 - Spin resolved bandstructure imaging with a high resolution momentum microscope [Crossref]
  5. 2023 - Soft x-ray photoelectron momentum microscope for multimodal valence band stereography [Crossref]
  6. 2024 - Performance of a photoelectron momentum microscope in direct- and momentum-space imaging with ultraviolet photon sources [Crossref]
  7. 2024 - Visualization of spin-polarized electronic states by imaging-type spin-resolved photoemission microscopy
  8. 2017 - Direct 3D mapping of the fermi surface and fermi velocity [Crossref]
  9. 2019 - Progress in HAXPES performance combining full-field k-imaging with time-of-flight recording [Crossref]
  10. 2021 - Bulk spin polarization of magnetite from spin-resolved hard X-ray photoelectron spectroscopy [Crossref]

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