Time- and momentum-resolved photoemission studies using time-of-flight momentum microscopy at a free-electron laser

Abstract

Time-resolved photoemission with ultrafast pump and probe pulses is an emerging technique with wide application potential. Real-time recording of non-equilibrium electronic processes, transient states in chemical reactions or the interplay of electronic and structural dynamics offers fascinating opportunities for future research. Combining valence-band and core-level spectroscopy with photoelectron diffraction for electronic, chemical and structural analysis requires few 10 fs soft X-ray pulses with some 10 meV spectral resolution, which are currently available at high repetition rate free-electron lasers. The PG2 beamline at FLASH (DESY, Hamburg) provides a high pulse rate of 5000 pulses/s, 60 fs pulse duration and 40 meV bandwidth in an energy range of 25-830 eV with a photon beam size down to 50 microns in diameter. We have constructed and optimized a versatile setup commissioned at FLASH/PG2 that combines FEL capabilities together with a multidimensional recording scheme for photoemission studies. We use a full-field imaging momentum microscope with time-of-flight energy recording as the detector for mapping of 3D band structures in ($k_x$, $k_y$, $E$) parameter space with unprecedented efficiency. Our instrument can image full surface Brillouin zones with up to 7 Å ${}^{-1}$ diameter in a binding-energy range of several eV, resolving about $2.5\times 10^5$ data voxels. As an example, we present results for the ultrafast excited state dynamics in the model van der Waals semiconductor WSe${}_2$.

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• Valley polarization in MoS2 monolayers by optical pumping
• Excitons in atomically thin transition metal dichalcogenides
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• Topological Kondo Insulators
• Hidden spin polarization in inversion-symmetric bulk crystals
• A microprocessor based on a two-dimensional semiconductor
• Direct observation of spin-polarised bulk bands in an inversion-symmetric semiconductor
• Generation and evolution of spin-, valley- and layer-polarized excited carriers in inversion-symmetric WSe2
• Time- and angle-resolved photoemission spectroscopy of solids in the extreme ultraviolet at 500 kHz repetition rate
• Ultrafast extreme ultraviolet photoemission without space charge
• Cavity-enhanced high harmonic generation for XUV time-resolved ARPES
• The monochromator beamline at FLASH: performance, capabilities and upgrade plans
• A setup for extreme-ultraviolet ultrafast angle-resolved photoelectron spectroscopy at 50-kHz repetition rate
• Decoding the ultrafast formation of a Fermi-Dirac distributed electron gas
• Spin Mapping of Surface and Bulk Rashba States in Ferroelectric a-GeTe(111) Films
• Electron-hole balanced dynamics in the type-II Weyl semimetal candidate WTe2
• An open-source, end-to-end workflow for multidimensional photoemission spectroscopy
• Momentum-Transfer Model of Valence-Band Photoelectron Diffraction

Cited by in corpus (37)

• Electronic structure of quantum materials studied by angle-resolved photoemission spectroscopy
• Nonthermal pathways to ultrafast control in quantum materials
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• Angle-resolved photoemission spectroscopy
• Exciton optics, dynamics and transport in atomically thin semiconductors
• Time-Resolved Momentum Microscopy with a 1 MHz High-Harmonic Extreme Ultraviolet Beamline
• Observation of an excitonic Mott transition through ultrafast core-$\text{cum}$-conduction photoemission spectroscopy
• A quantitative comparison of time-of-flight momentum microscopes and hemispherical analyzers for time- and angle-resolved photoemission spectroscopy experiments
• Subpicosecond metamagnetic phase transition driven by non-equilibrium electron dynamics
• Tuning time and energy resolution in time-resolved photoemission spectroscopy with nonlinear crystals
• Non-equilibrium phenomena in superconductors probed by femtosecond time-domain spectroscopy
• Floquet topological phase of nondriven $p$-wave nonequilibrium excitonic insulators
• Ultrafast molecular orbital tomography of a pentacene thin film using time-resolved momentum microscopy at a free-electron laser
• Accessing the spectral function of in operando devices by angle-resolved photoemission spectroscopy
• Advancing time- and angle-resolved photoemission spectroscopy: The role of ultrafast laser development
• Ultrafast time- and angle-resolved photoemission spectroscopy with widely tunable probe photon energy of 5.3-7.0 eV for investigating dynamics of three-dimensional materials
• Single-Hemisphere Photoelectron Momentum Microscope With Time-of-Flight Recording
• Ultrafast electronic line width broadening in the C 1s core level of graphene
• Band structure tuning of Heusler compounds revisited: Spin- and momentum-resolved electronic structure analysis of compounds with different band filling
• A narrow bandwidth extreme ultra-violet light source for time- and angle-resolved photoemission spectroscopy
• Detecting light-induced Floquet band gaps of graphene via trARPES
• An open-source, end-to-end workflow for multidimensional photoemission spectroscopy
• Towards full surface Brillouin zone mapping by coherent multi-photon photoemission
• Structure Analysis using Time-of-Flight Momentum Microscopy with Hard X-rays: Status and Prospects
• Ultrafast nano-imaging of dark excitons
• Multispectral time-resolved energy-momentum microscopy using high-harmonic extreme ultraviolet radiation
• Spin- and time-resolved photoelectron spectroscopy and diffraction studies using time-of-flight momentum microscopes
• Probing excitons with time-resolved momentum microscopy
• Multi-Mode Lens for Momentum Microscopy and XPEEM: Theory
• Direct detection of odd-frequency superconductivity via time- and angle-resolved photoelectron fluctuation spectroscopy
• Photoemission from the gas phase using soft x-ray fs pulses: An investigation of the space-charge effects
• A minimalist approach to 3D photoemission orbital tomography: algorithms and data requirements
• Femtosecond concerted rotation of molecules on a 2D material interface
• Photoemission orbital tomography based on tight-binding approach: method and application to $\pi$-conjugated molecules
• Carrier-envelope phase effects in one- and two-photon directional photoionization of non-isotropic atomic states
• Clustering-Enhanced Time- and Angle-Resolved Photoemission Study of LaTe${}_3$: Absence of a Photoinduced Secondary CDW in the Electronic Structure
• Tracking the surface atomic motion in a coherent phonon oscillation