Dresden 2020 – scientific programme

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O: Fachverband Oberflächenphysik

O 112: Development of Novel Methods I

O 112.5: Talk

Thursday, March 19, 2020, 16:15–16:30, WIL C107

Photoelectron Momentum Imaging Using a Combination of Single Hemispherical Analyzer and Time-of-Flight Recording — •Katerina Medjanik, Sergey Babenkov, Dmitry Vasilyev, Hans-Joachim Elmers, and Gerd Schönhense — JGU, Institut für Physik, Mainz, Germany

Extensive work of Tusche et al. [1] uncovered principal advantages of the "non-inverted" operation of a double-hemispherical analyser, a concept that can be simplified to a large single hemispherical dispersive analyser (HDA). We implemented an additional time-of-flight (ToF) section behind the HDA as "booster" improving resolution. The time spread of the electrons passing the HDA is detrimental in standard operation [2] but is strictly deterministic in our instrument, because the momentum image is encoded as angular pattern in the analyzer. First data taken with laboratory sources show that the time spread (1-2 ns at typical settings) varies linearly with coordinate ky (dispersive direction) but does not affect kx. Combining the flexibility of the HDA with the advantage of 3D ToF-recording, the hybrid instrument increases detection efficiency by 1-2 orders of magnitude. It does not require special filling patterns of Synchrotron- and FEL-sources and will be most relevant for high-resolution and spin-resolved work in the soft- and hard-X-ray range, where ToF-recording has proven superior [3].

[1] Tusche et al., Ultramicr. 206, 112815 (2019); [2] Sise & Zouros, J. Spectroscopy 153513 (2015); [3] Medjanik et al., J. Synchr. Rad. 26, 1996 (2019).