title: Correction of the deterministic part of space-charge interaction in momentum microscopy of charged particles.
abstract: Ultrahigh spectral brightness femtosecond XUV and X-ray sources like free electron lasers (FEL) and table-top high harmonics sources (HHG) offer fascinating experimental possibilities for analysis of transient states and ultrafast electron dynamics. For electron spectroscopy experiments using illumination from such sources, the ultrashort high-charge electron bunches experience strong space-charge interactions. The Coulomb interactions between emitted electrons results in large energy shifts and severe broadening of photoemission signals. We propose a method for a substantial reduction of the effect by exploiting the deterministic nature of space-charge interaction. The interaction of a given electron with the average charge density of all surrounding electrons leads to a rotation of the electron distribution in 6D phase space. Momentum microscopy gives direct access to the three momentum coordinates, opening a path for a correction of an essential part of space-charge interaction. In a first experiment with a time-of-flight momentum microscope using synchrotron radiation at BESSY, the rotation in phase space became directly visible. In a separate experiment conducted at FLASH (DESY), the energy shift and broadening of the photoemission signals were quantified. Finally, simulations of a realistic photoemission experiment including space-charge interaction reveals that a gain of an order of magnitude in resolution is possible using the correction technique presented here.
authors.affiliation: Institut für Physik, Johannes Gutenberg-Universität, 55128 Mainz, Germany. Electronic address: schoenhense@uni-mainz.de.
authors.forename: G
authors.initials: G
authors.lastname: Schönhense
authors.affiliation: Institut für Physik, Johannes Gutenberg-Universität, 55128 Mainz, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Medjanik
authors.affiliation: Max-Planck-Institut für Mikrostrukturphysik, 06120 Halle, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Tusche
authors.affiliation: Pulsar Physics, Burghstraat 47, 5614 BC Eindhoven, The Netherlands.
authors.forename: M
authors.initials: M
authors.lastname: de Loos
authors.affiliation: Pulsar Physics, Burghstraat 47, 5614 BC Eindhoven, The Netherlands.
authors.forename: B
authors.initials: B
authors.lastname: van der Geer
authors.affiliation: Physics Department and Center for Free-Electron Laser Science, Univ. Hamburg, 22761 Hamburg, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Scholz
authors.affiliation: Physics Department and Center for Free-Electron Laser Science, Univ. Hamburg, 22761 Hamburg, Germany.
authors.forename: F
authors.initials: F
authors.lastname: Hieke
authors.affiliation: Physics Department and Center for Free-Electron Laser Science, Univ. Hamburg, 22761 Hamburg, Germany.
authors.forename: N
authors.initials: N
authors.lastname: Gerken
authors.affiliation: Max-Planck-Institut für Mikrostrukturphysik, 06120 Halle, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Kirschner
authors.affiliation: Physics Department and Center for Free-Electron Laser Science, Univ. Hamburg, 22761 Hamburg, Germany; DESY Photon Science, 22607 Hamburg, Germany.
authors.forename: W
authors.initials: W
authors.lastname: Wurth
keywords: HAXPES; Momentum microscopy; Space charge