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Ultrafast orbital tomography of a pentacene film using time-resolved momentum microscopy at a FEL. Nat Commun 2022; 13:2741. [PMID: 35585096 PMCID: PMC9117673 DOI: 10.1038/s41467-022-30404-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Accepted: 04/28/2022] [Indexed: 11/24/2022] Open
Abstract
Time-resolved momentum microscopy provides insight into the ultrafast interplay between structural and electronic dynamics. Here we extend orbital tomography into the time domain in combination with time-resolved momentum microscopy at a free-electron laser (FEL) to follow transient photoelectron momentum maps of excited states of a bilayer pentacene film on Ag(110). We use optical pump and FEL probe pulses by keeping FEL source conditions to minimize space charge effects and radiation damage. From the momentum microscopy signal, we obtain time-dependent momentum maps of the excited-state dynamics of both pentacene layers separately. In a combined experimental and theoretical study, we interpret the observed signal for the bottom layer as resulting from the charge redistribution between the molecule and the substrate induced by excitation. We identify that the dynamics of the top pentacene layer resembles excited-state molecular dynamics. Ultrafast pulses are useful to investigate the electron dynamics in excited atoms, molecules and other complex systems. Here, the authors measure transient photoelectron momentum maps following the free-electron laser pulse-induced ionization of a bilayer pentacene thin film on Ag (110) by using time-resolved orbital tomography.
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Schönhense G, Medjanik K, Fedchenko O, Zymaková A, Chernov S, Kutnyakhov D, Vasilyev D, Babenkov S, Elmers HJ, Baumgärtel P, Goslawski P, Öhrwall G, Grunske T, Kauerhof T, von Volkmann K, Kallmayer M, Ellguth M, Oelsner A. Time-of-flight photoelectron momentum microscopy with 80-500 MHz photon sources: electron-optical pulse picker or bandpass pre-filter. JOURNAL OF SYNCHROTRON RADIATION 2021; 28:1891-1908. [PMID: 34738944 PMCID: PMC8570213 DOI: 10.1107/s1600577521010511] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Accepted: 10/10/2021] [Indexed: 06/13/2023]
Abstract
The small time gaps of synchrotron radiation in conventional multi-bunch mode (100-500 MHz) or laser-based sources with high pulse rate (∼80 MHz) are prohibitive for time-of-flight (ToF) based photoelectron spectroscopy. Detectors with time resolution in the 100 ps 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 MAX II) and 1.25 MHz (at BESSY II). 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-µm-ARPES' the ROI is defined by a small field aperture in an intermediate Gaussian image, regardless of the size of the photon spot.
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Affiliation(s)
- G. Schönhense
- Institut für Physik, Johannes Gutenberg Universität, 55128 Mainz, Germany
| | - K. Medjanik
- Institut für Physik, Johannes Gutenberg Universität, 55128 Mainz, Germany
| | - O. Fedchenko
- Institut für Physik, Johannes Gutenberg Universität, 55128 Mainz, Germany
| | - A. Zymaková
- Institut für Physik, Johannes Gutenberg Universität, 55128 Mainz, Germany
| | - S. Chernov
- Institut für Physik, Johannes Gutenberg Universität, 55128 Mainz, Germany
| | - D. Kutnyakhov
- Institut für Physik, Johannes Gutenberg Universität, 55128 Mainz, Germany
| | - D. Vasilyev
- Institut für Physik, Johannes Gutenberg Universität, 55128 Mainz, Germany
| | - S. Babenkov
- Institut für Physik, Johannes Gutenberg Universität, 55128 Mainz, Germany
| | - H. J. Elmers
- Institut für Physik, Johannes Gutenberg Universität, 55128 Mainz, Germany
| | | | - P. Goslawski
- BESSY II, Helmholtz-Zentrum, 12489 Berlin, Germany
| | - G. Öhrwall
- MAX IV Laboratory, Lund University, PO Box 118, SE-221 00 Lund, Sweden
| | | | | | | | | | - M. Ellguth
- Surface Concept GmbH, 55128 Mainz, Germany
| | - A. Oelsner
- Surface Concept GmbH, 55128 Mainz, Germany
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3
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Schönhense G, Kutnyakhov D, Pressacco F, Heber M, Wind N, Agustsson SY, Babenkov S, Vasilyev D, Fedchenko O, Chernov S, Rettig L, Schönhense B, Wenthaus L, Brenner G, Dziarzhytski S, Palutke S, Mahatha SK, Schirmel N, Redlin H, Manschwetus B, Hartl I, Matveyev Y, Gloskovskii A, Schlueter C, Shokeen V, Duerr H, Allison TK, Beye M, Rossnagel K, Elmers HJ, Medjanik K. Suppression of the vacuum space-charge effect in fs-photoemission by a retarding electrostatic front lens. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:053703. [PMID: 34243258 DOI: 10.1063/5.0046567] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Accepted: 04/04/2021] [Indexed: 06/13/2023]
Abstract
The performance of time-resolved photoemission experiments at fs-pulsed photon sources is ultimately limited by the e-e Coulomb interaction, downgrading energy and momentum resolution. Here, we present an approach to effectively suppress space-charge artifacts in momentum microscopes and photoemission microscopes. A retarding electrostatic field generated by a special objective lens repels slow electrons, retaining the k-image of the fast photoelectrons. The suppression of space-charge effects scales with the ratio of the photoelectron velocities of fast and slow electrons. Fields in the range from -20 to -1100 V/mm for Ekin = 100 eV to 4 keV direct secondaries and pump-induced slow electrons back to the sample surface. Ray tracing simulations reveal that this happens within the first 40 to 3 μm above the sample surface for Ekin = 100 eV to 4 keV. An optimized front-lens design allows switching between the conventional accelerating and the new retarding mode. Time-resolved experiments at Ekin = 107 eV using fs extreme ultraviolet probe pulses from the free-electron laser FLASH reveal that the width of the Fermi edge increases by just 30 meV at an incident pump fluence of 22 mJ/cm2 (retarding field -21 V/mm). For an accelerating field of +2 kV/mm and a pump fluence of only 5 mJ/cm2, it increases by 0.5 eV (pump wavelength 1030 nm). At the given conditions, the suppression mode permits increasing the slow-electron yield by three to four orders of magnitude. The feasibility of the method at high energies is demonstrated without a pump beam at Ekin = 3830 eV using hard x rays from the storage ring PETRA III. The approach opens up a previously inaccessible regime of pump fluences for photoemission experiments.
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Affiliation(s)
- G Schönhense
- Johannes Gutenberg-Universität, Institut für Physik, D-55099 Mainz, Germany
| | - D Kutnyakhov
- Deutsches Elektronen-Synchrotron DESY, D-22607 Hamburg, Germany
| | - F Pressacco
- Deutsches Elektronen-Synchrotron DESY, D-22607 Hamburg, Germany
| | - M Heber
- Deutsches Elektronen-Synchrotron DESY, D-22607 Hamburg, Germany
| | - N Wind
- University of Hamburg, Institut für Experimentalphysik, D-22761 Hamburg, Germany
| | - S Y Agustsson
- Johannes Gutenberg-Universität, Institut für Physik, D-55099 Mainz, Germany
| | - S Babenkov
- Johannes Gutenberg-Universität, Institut für Physik, D-55099 Mainz, Germany
| | - D Vasilyev
- Johannes Gutenberg-Universität, Institut für Physik, D-55099 Mainz, Germany
| | - O Fedchenko
- Johannes Gutenberg-Universität, Institut für Physik, D-55099 Mainz, Germany
| | - S Chernov
- Departments of Chemistry and Physics, Stony Brook University, Stony Brook, New York 11790-3400, USA
| | - L Rettig
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, D-14195 Berlin, Germany
| | - B Schönhense
- Department of Bioengineering, Imperial College London, South Kensington Campus, London SW7 2AZ, United Kingdom
| | - L Wenthaus
- Deutsches Elektronen-Synchrotron DESY, D-22607 Hamburg, Germany
| | - G Brenner
- Deutsches Elektronen-Synchrotron DESY, D-22607 Hamburg, Germany
| | - S Dziarzhytski
- Deutsches Elektronen-Synchrotron DESY, D-22607 Hamburg, Germany
| | - S Palutke
- Deutsches Elektronen-Synchrotron DESY, D-22607 Hamburg, Germany
| | - S K Mahatha
- Ruprecht Haensel Laboratory, Deutsches Elektronen-Synchrotron DESY, D-22607 Hamburg, Germany
| | - N Schirmel
- Deutsches Elektronen-Synchrotron DESY, D-22607 Hamburg, Germany
| | - H Redlin
- Deutsches Elektronen-Synchrotron DESY, D-22607 Hamburg, Germany
| | - B Manschwetus
- Deutsches Elektronen-Synchrotron DESY, D-22607 Hamburg, Germany
| | - I Hartl
- Deutsches Elektronen-Synchrotron DESY, D-22607 Hamburg, Germany
| | - Yu Matveyev
- Deutsches Elektronen-Synchrotron DESY, D-22607 Hamburg, Germany
| | - A Gloskovskii
- Deutsches Elektronen-Synchrotron DESY, D-22607 Hamburg, Germany
| | - C Schlueter
- Deutsches Elektronen-Synchrotron DESY, D-22607 Hamburg, Germany
| | - V Shokeen
- Department of Physics and Astronomy, Uppsala University, P.O. Box 516, 75120 Uppsala, Sweden
| | - H Duerr
- Department of Physics and Astronomy, Uppsala University, P.O. Box 516, 75120 Uppsala, Sweden
| | - T K Allison
- Departments of Chemistry and Physics, Stony Brook University, Stony Brook, New York 11790-3400, USA
| | - M Beye
- Deutsches Elektronen-Synchrotron DESY, D-22607 Hamburg, Germany
| | - K Rossnagel
- Ruprecht Haensel Laboratory, Deutsches Elektronen-Synchrotron DESY, D-22607 Hamburg, Germany
| | - H J Elmers
- Johannes Gutenberg-Universität, Institut für Physik, D-55099 Mainz, Germany
| | - K Medjanik
- Johannes Gutenberg-Universität, Institut für Physik, D-55099 Mainz, Germany
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Kutnyakhov D, Xian RP, Dendzik M, Heber M, Pressacco F, Agustsson SY, Wenthaus L, Meyer H, Gieschen S, Mercurio G, Benz A, Bühlman K, Däster S, Gort R, Curcio D, Volckaert K, Bianchi M, Sanders C, Miwa JA, Ulstrup S, Oelsner A, Tusche C, Chen YJ, Vasilyev D, Medjanik K, Brenner G, Dziarzhytski S, Redlin H, Manschwetus B, Dong S, Hauer J, Rettig L, Diekmann F, Rossnagel K, Demsar J, Elmers HJ, Hofmann P, Ernstorfer R, Schönhense G, Acremann Y, Wurth W. Time- and momentum-resolved photoemission studies using time-of-flight momentum microscopy at a free-electron laser. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2020; 91:013109. [PMID: 32012554 DOI: 10.1063/1.5118777] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Accepted: 11/30/2019] [Indexed: 06/10/2023]
Abstract
Time-resolved photoemission with ultrafast pump and probe pulses is an emerging technique with wide application potential. Real-time recording of nonequilibrium 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 analyses 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. We have constructed and optimized a versatile setup commissioned at FLASH/PG2 that combines free-electron laser 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 (kx, ky, 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 × 105 data voxels simultaneously. Using the ultrafast excited state dynamics in the van der Waals semiconductor WSe2 measured at photon energies of 36.5 eV and 109.5 eV, we demonstrate an experimental energy resolution of 130 meV, a momentum resolution of 0.06 Å-1, and a system response function of 150 fs.
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Affiliation(s)
- D Kutnyakhov
- Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
| | - R P Xian
- Fritz Haber Institute of the Max Planck Society, 14195 Berlin, Germany
| | - M Dendzik
- Fritz Haber Institute of the Max Planck Society, 14195 Berlin, Germany
| | - M Heber
- Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
| | - F Pressacco
- Physics Department and Centre for Free-Electron Laser Science (CFEL), University of Hamburg, 22761 Hamburg, Germany
| | - S Y Agustsson
- Institut für Physik, Johannes Gutenberg-Universität Mainz, 55128 Mainz, Germany
| | - L Wenthaus
- Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
| | - H Meyer
- Physics Department and Centre for Free-Electron Laser Science (CFEL), University of Hamburg, 22761 Hamburg, Germany
| | - S Gieschen
- Physics Department and Centre for Free-Electron Laser Science (CFEL), University of Hamburg, 22761 Hamburg, Germany
| | - G Mercurio
- Physics Department and Centre for Free-Electron Laser Science (CFEL), University of Hamburg, 22761 Hamburg, Germany
| | - A Benz
- Physics Department and Centre for Free-Electron Laser Science (CFEL), University of Hamburg, 22761 Hamburg, Germany
| | - K Bühlman
- Laboratorium für Festkörperphysik, ETH Zürich, 8093 Zürich, Switzerland
| | - S Däster
- Laboratorium für Festkörperphysik, ETH Zürich, 8093 Zürich, Switzerland
| | - R Gort
- Laboratorium für Festkörperphysik, ETH Zürich, 8093 Zürich, Switzerland
| | - D Curcio
- Department of Physics and Astronomy, Interdisciplinary Nanoscience Center (iNANO), Aarhus University, 8000 Aarhus C, Denmark
| | - K Volckaert
- Department of Physics and Astronomy, Interdisciplinary Nanoscience Center (iNANO), Aarhus University, 8000 Aarhus C, Denmark
| | - M Bianchi
- Department of Physics and Astronomy, Interdisciplinary Nanoscience Center (iNANO), Aarhus University, 8000 Aarhus C, Denmark
| | - Ch Sanders
- Central Laser Facility, STFC Rutherford Appleton Laboratory, Harwell OX11 0QX, United Kingdom
| | - J A Miwa
- Department of Physics and Astronomy, Interdisciplinary Nanoscience Center (iNANO), Aarhus University, 8000 Aarhus C, Denmark
| | - S Ulstrup
- Department of Physics and Astronomy, Interdisciplinary Nanoscience Center (iNANO), Aarhus University, 8000 Aarhus C, Denmark
| | - A Oelsner
- Surface Concept GmbH, 55124 Mainz, Germany
| | - C Tusche
- Forschungszentrum Jülich GmbH, Peter Grünberg Institut (PGI-6), 52428 Jülich, Germany
| | - Y-J Chen
- Forschungszentrum Jülich GmbH, Peter Grünberg Institut (PGI-6), 52428 Jülich, Germany
| | - D Vasilyev
- Institut für Physik, Johannes Gutenberg-Universität Mainz, 55128 Mainz, Germany
| | - K Medjanik
- Institut für Physik, Johannes Gutenberg-Universität Mainz, 55128 Mainz, Germany
| | - G Brenner
- Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
| | - S Dziarzhytski
- Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
| | - H Redlin
- Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
| | - B Manschwetus
- Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
| | - S Dong
- Fritz Haber Institute of the Max Planck Society, 14195 Berlin, Germany
| | - J Hauer
- Fritz Haber Institute of the Max Planck Society, 14195 Berlin, Germany
| | - L Rettig
- Fritz Haber Institute of the Max Planck Society, 14195 Berlin, Germany
| | - F Diekmann
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany
| | - K Rossnagel
- Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
| | - J Demsar
- Institut für Physik, Johannes Gutenberg-Universität Mainz, 55128 Mainz, Germany
| | - H-J Elmers
- Institut für Physik, Johannes Gutenberg-Universität Mainz, 55128 Mainz, Germany
| | - Ph Hofmann
- Department of Physics and Astronomy, Interdisciplinary Nanoscience Center (iNANO), Aarhus University, 8000 Aarhus C, Denmark
| | - R Ernstorfer
- Fritz Haber Institute of the Max Planck Society, 14195 Berlin, Germany
| | - G Schönhense
- Institut für Physik, Johannes Gutenberg-Universität Mainz, 55128 Mainz, Germany
| | - Y Acremann
- Laboratorium für Festkörperphysik, ETH Zürich, 8093 Zürich, Switzerland
| | - W Wurth
- Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
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5
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Medjanik K, Babenkov SV, Chernov S, Vasilyev D, Schönhense B, Schlueter C, Gloskovskii A, Matveyev Y, Drube W, Elmers HJ, Schönhense G. Progress in HAXPES performance combining full-field k-imaging with time-of-flight recording. JOURNAL OF SYNCHROTRON RADIATION 2019; 26:1996-2012. [PMID: 31721745 PMCID: PMC6853377 DOI: 10.1107/s1600577519012773] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Accepted: 09/13/2019] [Indexed: 05/27/2023]
Abstract
An alternative approach to hard-X-ray photoelectron spectroscopy (HAXPES) has been established. The instrumental key feature is an increase of the dimensionality of the recording scheme from 2D to 3D. A high-energy momentum microscope detects electrons with initial kinetic energies up to 8 keV with a k-resolution of 0.025 Å-1, equivalent to an angular resolution of 0.034°. A special objective lens with k-space acceptance up to 25 Å-1 allows for simultaneous full-field imaging of many Brillouin zones. Combined with time-of-flight (ToF) parallel energy recording this yields maximum parallelization. Thanks to the high brilliance (1013 hν s-1 in a spot of <20 µm diameter) of beamline P22 at PETRA III (Hamburg, Germany), the microscope set a benchmark in HAXPES recording speed, i.e. several million counts per second for core-level signals and one million for d-bands of transition metals. The concept of tomographic k-space mapping established using soft X-rays works equally well in the hard X-ray range. Sharp valence band k-patterns of Re, collected at an excitation energy of 6 keV, correspond to direct transitions to the 28th repeated Brillouin zone. Measured total energy resolutions (photon bandwidth plus ToF-resolution) are 62 meV and 180 meV FWHM at 5.977 keV for monochromator crystals Si(333) and Si(311) and 450 meV at 4.0 keV for Si(111). Hard X-ray photoelectron diffraction (hXPD) patterns with rich fine structure are recorded within minutes. The short photoelectron wavelength (10% of the interatomic distance) `amplifies' phase differences, making full-field hXPD a sensitive structural tool.
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Affiliation(s)
- K. Medjanik
- Institut für Physik, Johannes Gutenberg Universität Mainz, D-55099 Mainz, Germany
| | - S. V. Babenkov
- Institut für Physik, Johannes Gutenberg Universität Mainz, D-55099 Mainz, Germany
| | - S. Chernov
- Institut für Physik, Johannes Gutenberg Universität Mainz, D-55099 Mainz, Germany
| | - D. Vasilyev
- Institut für Physik, Johannes Gutenberg Universität Mainz, D-55099 Mainz, Germany
| | - B. Schönhense
- Department of Bioengineering, Imperial College London, UK
| | - C. Schlueter
- DESY Photon Science, Notkestrasse 85, 22607 Hamburg, Germany
| | - A. Gloskovskii
- DESY Photon Science, Notkestrasse 85, 22607 Hamburg, Germany
| | - Yu. Matveyev
- DESY Photon Science, Notkestrasse 85, 22607 Hamburg, Germany
| | - W. Drube
- DESY Photon Science, Notkestrasse 85, 22607 Hamburg, Germany
| | - H. J. Elmers
- Institut für Physik, Johannes Gutenberg Universität Mainz, D-55099 Mainz, Germany
| | - G. Schönhense
- Institut für Physik, Johannes Gutenberg Universität Mainz, D-55099 Mainz, Germany
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Imaging properties of hemispherical electrostatic energy analyzers for high resolution momentum microscopy. Ultramicroscopy 2019; 206:112815. [PMID: 31325896 DOI: 10.1016/j.ultramic.2019.112815] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2018] [Accepted: 07/07/2019] [Indexed: 11/20/2022]
Abstract
Hemispherical deflection analyzers are the most widely used energy filters for state-of-the-art electron spectroscopy. Due to the high spherical symmetry, they are also well suited as imaging energy filters for electron microscopy. Here, we review the imaging properties of hemispherical deflection analyzers with emphasis on the application for cathode lens microscopy. In particular, it turns out that aberrations, in general limiting the image resolution, cancel out at the entrance and exit of the analyzer. This finding allows more compact imaging energy filters for momentum microscopy or photoelectron emission microscopy. For instance, high resolution imaging is possible, using only a single hemisphere. Conversely, a double pass hemispherical analyzer can double the energy dispersion, which means it can double the energy resolution at certain transmission, or can multiply the transmission at certain energy resolution.
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7
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Schönhense G, Medjanik K, Chernov S, Kutnyakhov D, Fedchenko O, Ellguth M, Vasilyev D, Zaporozhchenko-Zymaková A, Panzer D, Oelsner A, Tusche C, Schönhense B, Braun J, Minár J, Ebert H, Viefhaus J, Wurth W, Elmers HJ. Spin-filtered time-of-flight k-space microscopy of Ir - Towards the "complete" photoemission experiment. Ultramicroscopy 2017; 183:19-29. [PMID: 28705441 DOI: 10.1016/j.ultramic.2017.06.025] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2017] [Revised: 06/16/2017] [Accepted: 06/28/2017] [Indexed: 11/28/2022]
Abstract
The combination of momentum microscopy (high resolution imaging of the Fourier plane) with an imaging spin filter has recently set a benchmark in k-resolution and spin-detection efficiency. Here we show that the degree of parallelization can be further increased by time-of-flight energy recording. On the quest towards maximum information (in earlier work termed "complete" photoemission experiment) we have studied the prototypical high-Z fcc metal iridium. Large partial bandgaps and strong spin-orbit interaction lead to a sequence of spin-polarized surface resonances. Soft X-rays give access to the 4D spectral density function ρ (EB,kx,ky,kz) weighted by the photoemission cross section. The Fermi surface and all other energy isosurfaces, Fermi velocity distribution vF(kF), electron or hole conductivity, effective mass and inner potential can be obtained from the multi-dimensional array ρ by simple algorithms. Polarized light reveals the linear and circular dichroism texture in a simple manner and an imaging spin filter exposes the spin texture. One-step photoemission calculations are in fair agreement with experiment. Comparison of the Bloch spectral function with photoemission calculations uncovers that the observed high spin polarization of photoelectrons from bulk bands originates from the photoemission step and is not present in the initial state.
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Affiliation(s)
- G Schönhense
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, 55099 Mainz, Germany.
| | - K Medjanik
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, 55099 Mainz, Germany
| | - S Chernov
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, 55099 Mainz, Germany
| | - D Kutnyakhov
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, 55099 Mainz, Germany; DESY, Hamburg, Germany
| | - O Fedchenko
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, 55099 Mainz, Germany
| | - M Ellguth
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, 55099 Mainz, Germany
| | - D Vasilyev
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, 55099 Mainz, Germany
| | | | - D Panzer
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, 55099 Mainz, Germany; Surface Concept GmbH, Am Sägewerk 23a, 55124 Mainz, Germany
| | - A Oelsner
- Surface Concept GmbH, Am Sägewerk 23a, 55124 Mainz, Germany
| | - C Tusche
- Peter Grünberg Institut (PGI-6), Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
| | - B Schönhense
- Department of Bioengineering, Imperial College London, UK
| | - J Braun
- Department Chemie, Ludwig-Maximilians-Universität München, 81377 Munich, Germany
| | - J Minár
- Department Chemie, Ludwig-Maximilians-Universität München, 81377 Munich, Germany; New Technologies-Research Center, University of West Bohemia, Pilsen, Czech Republic
| | - H Ebert
- Department Chemie, Ludwig-Maximilians-Universität München, 81377 Munich, Germany
| | | | - W Wurth
- DESY, Hamburg, Germany; Physics Department and CFEL, University of Hamburg, Germany
| | - H J Elmers
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, 55099 Mainz, Germany
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8
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Medjanik K, Fedchenko O, Chernov S, Kutnyakhov D, Ellguth M, Oelsner A, Schönhense B, Peixoto TRF, Lutz P, Min CH, Reinert F, Däster S, Acremann Y, Viefhaus J, Wurth W, Elmers HJ, Schönhense G. Direct 3D mapping of the Fermi surface and Fermi velocity. NATURE MATERIALS 2017; 16:615-621. [PMID: 28272500 DOI: 10.1038/nmat4875] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Accepted: 02/03/2017] [Indexed: 05/13/2023]
Abstract
We performed a full mapping of the bulk electronic structure including the Fermi surface and Fermi-velocity distribution vF(kF) of tungsten. The 4D spectral function ρ(EB; k) in the entire bulk Brillouin zone and 6 eV binding-energy (EB) interval was acquired in ∼3 h thanks to a new multidimensional photoemission data-recording technique (combining full-field k-microscopy with time-of-flight parallel energy recording) and the high brilliance of the soft X-rays used. A direct comparison of bulk and surface spectral functions (taken at low photon energies) reveals a time-reversal-invariant surface state in a local bandgap in the (110)-projected bulk band structure. The surface state connects hole and electron pockets that would otherwise be separated by an indirect local bandgap. We confirmed its Dirac-like spin texture by spin-filtered momentum imaging. The measured 4D data array enables extraction of the 3D dispersion of all bands, all energy isosurfaces, electron velocities, hole or electron conductivity, effective mass and inner potential by simple algorithms without approximations. The high-Z bcc metals with large spin-orbit-induced bandgaps are discussed as candidates for topologically non-trivial surface states.
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Affiliation(s)
- K Medjanik
- Institut für Physik, Johannes Gutenberg-Universität, StaudingerWeg 7, 55128 Mainz, Germany
| | - O Fedchenko
- Institut für Physik, Johannes Gutenberg-Universität, StaudingerWeg 7, 55128 Mainz, Germany
| | - S Chernov
- Institut für Physik, Johannes Gutenberg-Universität, StaudingerWeg 7, 55128 Mainz, Germany
| | - D Kutnyakhov
- Institut für Physik, Johannes Gutenberg-Universität, StaudingerWeg 7, 55128 Mainz, Germany
- DESY Photon Science, Notkestraße 85, 22607 Hamburg, Germany
| | - M Ellguth
- Institut für Physik, Johannes Gutenberg-Universität, StaudingerWeg 7, 55128 Mainz, Germany
| | - A Oelsner
- Surface Concept GmbH, Am Sägewerk 23a, 55124 Mainz, Germany
| | - B Schönhense
- Department of Bioengineering, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
| | - T R F Peixoto
- Universität Würzburg, Experimentelle Physik VII, 97074 Würzburg, Germany
| | - P Lutz
- Universität Würzburg, Experimentelle Physik VII, 97074 Würzburg, Germany
| | - C-H Min
- Universität Würzburg, Experimentelle Physik VII, 97074 Würzburg, Germany
| | - F Reinert
- Universität Würzburg, Experimentelle Physik VII, 97074 Würzburg, Germany
| | - S Däster
- Laboratorium für Festkörperphysik, ETH Zürich, Otto-Stern-Weg 1, 8093 Zürich, Switzerland
| | - Y Acremann
- Laboratorium für Festkörperphysik, ETH Zürich, Otto-Stern-Weg 1, 8093 Zürich, Switzerland
| | - J Viefhaus
- DESY Photon Science, Notkestraße 85, 22607 Hamburg, Germany
| | - W Wurth
- DESY Photon Science, Notkestraße 85, 22607 Hamburg, Germany
- Physics Department and Center for Free-Electron Laser Science, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
| | - H J Elmers
- Institut für Physik, Johannes Gutenberg-Universität, StaudingerWeg 7, 55128 Mainz, Germany
| | - G Schönhense
- Institut für Physik, Johannes Gutenberg-Universität, StaudingerWeg 7, 55128 Mainz, Germany
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9
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Oloff LP, Chainani A, Matsunami M, Takahashi K, Togashi T, Osawa H, Hanff K, Quer A, Matsushita R, Shiraishi R, Nagashima M, Kimura A, Matsuishi K, Yabashi M, Tanaka Y, Rossi G, Ishikawa T, Rossnagel K, Oura M. Time-resolved HAXPES using a microfocused XFEL beam: From vacuum space-charge effects to intrinsic charge-carrier recombination dynamics. Sci Rep 2016; 6:35087. [PMID: 27731408 PMCID: PMC5059660 DOI: 10.1038/srep35087] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Accepted: 09/21/2016] [Indexed: 12/05/2022] Open
Abstract
Time-resolved hard X-ray photoelectron spectroscopy (trHAXPES) using microfocused X-ray free-electron laser (XFEL, hν = 8 keV) pulses as a probe and infrared laser pulses (hν = 1.55 eV) as a pump is employed to determine intrinsic charge-carrier recombination dynamics in La:SrTiO3. By means of a combination of experiments and numerical N-body simulations, we first develop a simple approach to characterize and decrease XFEL-induced vacuum space-charge effects, which otherwise pose a serious limitation to spectroscopy experiments. We then show that, using an analytical mean-field model, vacuum space-charge effects can be counteracted by pump laser-induced photoholes at high excitation densities. This provides us a method to separate vacuum space-charge effects from the intrinsic charge-carrier recombination dynamics in the time domain. Our trHAXPES results thus open a route to studies of intrinsic charge-carrier dynamics on picosecond time scales with lateral spatial resolution on the micrometer scale.
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Affiliation(s)
- Lars-Philip Oloff
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany.,RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan
| | - Ashish Chainani
- RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan
| | - Masaharu Matsunami
- RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan.,Toyota Technological Institute, Nagoya 468-8511, Japan
| | - Kazutoshi Takahashi
- RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan.,Synchrotron Light Application Center, Saga University, 1 Honjo, Saga 840-8502, Japan
| | - Tadashi Togashi
- RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan.,JASRI, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198, Japan
| | - Hitoshi Osawa
- JASRI, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198, Japan
| | - Kerstin Hanff
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany
| | - Arndt Quer
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany
| | - Ryuki Matsushita
- RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan.,Graduate School of Materials Science, University of Hyogo, Kamigori-cho, Ako-gun, Hyogo 678-1297, Japan
| | - Ryutaro Shiraishi
- RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan.,Graduate School of Materials Science, University of Hyogo, Kamigori-cho, Ako-gun, Hyogo 678-1297, Japan
| | - Maki Nagashima
- RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan.,Graduate School of Materials Science, University of Hyogo, Kamigori-cho, Ako-gun, Hyogo 678-1297, Japan
| | - Ayato Kimura
- RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan.,Graduate School of Materials Science, University of Hyogo, Kamigori-cho, Ako-gun, Hyogo 678-1297, Japan
| | - Kotaro Matsuishi
- RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan.,Synchrotron Light Application Center, Saga University, 1 Honjo, Saga 840-8502, Japan
| | - Makina Yabashi
- RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan.,JASRI, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198, Japan
| | - Yoshihito Tanaka
- RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan.,Graduate School of Materials Science, University of Hyogo, Kamigori-cho, Ako-gun, Hyogo 678-1297, Japan
| | - Giorgio Rossi
- Dipartimento di Fisica, Università degli Studi di Milano, Via Celoria 16, 20133 Milano, Italy
| | - Tetsuya Ishikawa
- RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan
| | - Kai Rossnagel
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany.,RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan
| | - Masaki Oura
- RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan
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10
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Schiwietz G, Kühn D, Föhlisch A, Holldack K, Kachel T, Pontius N. Laser-pump/X-ray-probe experiments with electrons ejected from a Cu(111) target: space-charge acceleration. JOURNAL OF SYNCHROTRON RADIATION 2016; 23:1158-1170. [PMID: 27577771 DOI: 10.1107/s1600577516009115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Accepted: 06/06/2016] [Indexed: 06/06/2023]
Abstract
A comprehensive investigation of the emission characteristics for electrons induced by X-rays of a few hundred eV at grazing-incidence angles on an atomically clean Cu(111) sample during laser excitation is presented. Electron energy spectra due to intense infrared laser irradiation are investigated at the BESSY II slicing facility. Furthermore, the influence of the corresponding high degree of target excitation (high peak current of photoemission) on the properties of Auger and photoelectrons liberated by a probe X-ray beam is investigated in time-resolved pump and probe measurements. Strong electron energy shifts have been found and assigned to space-charge acceleration. The variation of the shift with laser power and electron energy is investigated and discussed on the basis of experimental as well as new theoretical results.
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Affiliation(s)
- G Schiwietz
- Institut Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung (FG-ISRR), Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Hahn-Meitner-Platz 1, 14109 Berlin, Germany
| | - D Kühn
- Institut Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung (FG-ISRR), Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Hahn-Meitner-Platz 1, 14109 Berlin, Germany
| | - A Föhlisch
- Institut Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung (FG-ISRR), Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Hahn-Meitner-Platz 1, 14109 Berlin, Germany
| | - K Holldack
- Institut Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung (FG-ISRR), Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Hahn-Meitner-Platz 1, 14109 Berlin, Germany
| | - T Kachel
- Institut Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung (FG-ISRR), Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Hahn-Meitner-Platz 1, 14109 Berlin, Germany
| | - N Pontius
- Institut Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung (FG-ISRR), Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Hahn-Meitner-Platz 1, 14109 Berlin, Germany
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11
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Chernov SV, Medjanik K, Tusche C, Kutnyakhov D, Nepijko SA, Oelsner A, Braun J, Minár J, Borek S, Ebert H, Elmers HJ, Kirschner J, Schönhense G. Anomalous d-like surface resonances on Mo(110) analyzed by time-of-flight momentum microscopy. Ultramicroscopy 2015; 159 Pt 3:453-63. [PMID: 26363904 DOI: 10.1016/j.ultramic.2015.07.008] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Revised: 05/26/2015] [Accepted: 07/16/2015] [Indexed: 11/28/2022]
Abstract
The electronic surface states on Mo(110) have been investigated using time-of-flight momentum microscopy with synchrotron radiation (hν=35 eV). This novel angle-resolved photoemission approach yields a simultaneous acquisition of the E-vs-k spectral function in the full surface Brillouin zone and several eV energy interval. (kx,ky,EB)-maps with 3.4 Å(-1) diameter reveal a rich structure of d-like surface resonances in the spin-orbit induced partial band gap. Calculations using the one-step model in its density matrix formulation predict an anomalous state with Dirac-like signature and Rashba spin texture crossing the bandgap at Γ¯ and EB=1.2 eV. The experiment shows that the linear dispersion persists away from the Γ¯-point in an extended energy- and k∥-range. Analogously to a similar state previously found on W(110) the dispersion is linear along H¯-Γ¯-H¯ and almost zero along N¯-Γ¯-N¯. The similarity is surprising since the spin-orbit interaction is 5 times smaller in Mo. A second point with unusual topology is found midway between Γ¯ and N¯. Band symmetries are probed by linear dichroism.
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Affiliation(s)
- S V Chernov
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7, D-55128 Mainz, Germany
| | - K Medjanik
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7, D-55128 Mainz, Germany
| | - C Tusche
- Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, D-06120 Halle, Germany
| | - D Kutnyakhov
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7, D-55128 Mainz, Germany
| | - S A Nepijko
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7, D-55128 Mainz, Germany
| | - A Oelsner
- Surface Concept GmbH, Am Sägewerk 23A, D-55124 Mainz, Germany
| | - J Braun
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstrasse 5-13, D-81377 München, Germany
| | - J Minár
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstrasse 5-13, D-81377 München, Germany; New Technologies-Research Center, University of West Bohemia, Univerzitni 8, 306 14 Pilsen, Czech Republic
| | - S Borek
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstrasse 5-13, D-81377 München, Germany
| | - H Ebert
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstrasse 5-13, D-81377 München, Germany
| | - H J Elmers
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7, D-55128 Mainz, Germany
| | - J Kirschner
- Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, D-06120 Halle, Germany
| | - G Schönhense
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7, D-55128 Mainz, Germany.
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