Time-of-flight photoelectron momentum microscopy with 80–500 MHz photon sources: electron-optical pulse picker or bandpass pre-filter

Schönhense, G.; Medjanik, K.; Fedchenko, O.; Zymaková, A.; Chernov, S.; Kutnyakhov, D.; Vasilyev, D.; Babenkov, S.; Elmers, H.J.; Baumgärtel, P.; Goslawski, P.; Öhrwall, G.; Grunske, T.; Kauerhof, T.; von Volkmann, K.; Kallmayer, M.; Ellguth, M.; Oelsner, A.

doi:10.1107/S1600577521010511

Figure 4
Two ways of implementing time-of-flight recording at highly repetitive photon sources. The first is based on pulse-picking in the time domain by an HF deflector (a), the second on bandpass pre-selection in the energy domain by a dispersive element (b). Electron-optical elements and ray bundles schematic. In (a) the multi-bunch train of almost-overlapping spectra [Au 4f doublet (c)] is blanked by the HF deflector so that a single spectrum (d) with larger period passes the selector aperture. Spectrum (e) with the desired resolution is gained by ToF dispersion in the low-energy drift section. In the dispersive-plus-ToF hybrid instrument (b), the hemispherical analyzer (HSA) cuts a well defined bandpass [here W 4f doublet] from the full energy spectrum (f). The transmitted energy band is precisely selected via pass energy and slit widths. This pre-selected energy band is dispersed in the ToF drift section, leading to spectrum (g). In both cases the various lens groups can project either a momentum pattern or a real-space image on the delay-line detector (DLD). Auxiliary grids (retractable) in the backfocal plane of the objective lens and in the plane of the field aperture enable precise adjustment of the lens optics.

JOURNAL OF
SYNCHROTRON
RADIATION

ISSN: 1600-5775

Volume 28| Part 6| November 2021| Pages 1891-1908

https://doi.org/10.1107/S1600577521010511

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