TY  - JOUR
AU  - Schönhense, G.
AU  - Medjanik, K.
AU  - Fedchenko, O.
AU  - Zymakova, Anna
AU  - Chernov, S.
AU  - Kutnyakhov, Dmytro
AU  - Vasilyev, D.
AU  - Babenkov, S.
AU  - Elmers, H. J.
AU  - Baumgärtel, P.
AU  - Goslawski, P.
AU  - Öhrwall, G.
AU  - Grunske, T.
AU  - Kauerhof, T.
AU  - von Volkmann, K.
AU  - Kallmayer, M.
AU  - Ellguth, M.
AU  - Oelsner, A.
TI  - Time-of-flight photoelectron momentum microscopy with 80–500 MHz photon sources: electron-optical pulse picker or bandpass pre-filter
JO  - Journal of synchrotron radiation
VL  - 28
IS  - 6
SN  - 0909-0495
CY  - [S.l.]
PB  - Wiley-Blackwell
M1  - PUBDB-2021-05248
SP  - 1891 - 1908
PY  - 2021
AB  - The small time gaps of synchrotron radiation in conventional multi-bunch mode (100-500 MHz) or laser-based sources with high pulse rate (similar to 80 MHz) are prohibitive for time-of-flight (ToF) based photoelectron spectroscopy. Detectors with time resolution in the 100ps range yield only 20-100 resolved time slices within the small time gap. Here we present two techniques of implementing efficient ToF recording at sources with high repetition rate. A fast electron-optical beam blanking unit with GHz bandwidth, integrated in a photoelectron momentum microscope, allows electron-optical 'pulse-picking' with any desired repetition period. Aberration-free momentum distributions have been recorded at reduced pulse periods of 5 MHz (at MAXII) and 1.25 MHz (at BESSYII). The approach is compared with two alternative solutions: a bandpass pre-filter (here a hemispherical analyzer) or a parasitic four-bunch island-orbit pulse train, coexisting with the multi-bunch pattern on the main orbit. Chopping in the time domain or bandpass pre-selection in the energy domain can both enable efficient ToF spectroscopy and photoelectron momentum microscopy at 100-500 MHz synchrotrons, highly repetitive lasers or cavity-enhanced high-harmonic sources. The high photon flux of a UV-laser (80 MHz, <1 meV bandwidth) facilitates momentum microscopy with an energy resolution of 4.2 meV and an analyzed region-of-interest (ROI) down to < 800 nm. In this novel approach to `sub-mu m-ARPES' the ROI is defined by a small field aperture in an intermediate Gaussian image, regardless of the size of the photon spot.
LB  - PUB:(DE-HGF)16
C6  - 34738944
UR  - <Go to ISI:>//WOS:000715906300024
DO  - DOI:10.1107/S1600577521010511
UR  - https://bib-pubdb1.desy.de/record/472792
ER  -