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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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Aballe L, Foerster M, Cabrejo M, Prat J, Pittana P, Sergo R, Lucian M, Barnaba M, Menteş TO, Locatelli A. Pulse picking in synchrotron-based XPEEM. Ultramicroscopy 2019; 202:10-17. [PMID: 30928638 DOI: 10.1016/j.ultramic.2019.03.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2018] [Accepted: 03/18/2019] [Indexed: 10/27/2022]
Abstract
We report on a simple and cost-effective device for high-speed gating in photoemission electron microscopy (PEEM) with pulsed photon sources. This device is based on miniaturized electrode plates, which deflect the photoelectron beam inside the imaging column of the microscope so that it is either accepted or blocked in its path towards the detector. The gating device is optimized for installation on the Elmitec SPELEEM III microscope. Due to the compact design, it can be driven by voltage pulses of low amplitude (few volts), delivered by commercially available signal generators. Most notably, our device allows for stroboscopic data collection with on-time of less than 10 ns and at a rate in the range from 1 MHz to 250 MHz, making it suitable for usage in both hybrid and standard multi-bunch operation of the synchrotron ring. We demonstrate applications of pump-probe imaging at high lateral resolution, namely magnetic imaging and PEEM imaging of surface acoustic waves.
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Affiliation(s)
- Lucia Aballe
- ALBA Synchrotron, Carrer de la llum 2-26, 08290 Cerdanyola del Valles, Spain.
| | - Michael Foerster
- ALBA Synchrotron, Carrer de la llum 2-26, 08290 Cerdanyola del Valles, Spain
| | - Meritxell Cabrejo
- ALBA Synchrotron, Carrer de la llum 2-26, 08290 Cerdanyola del Valles, Spain
| | - Jordi Prat
- ALBA Synchrotron, Carrer de la llum 2-26, 08290 Cerdanyola del Valles, Spain
| | - Paolo Pittana
- Elettra-Sincrotrone Trieste, Strada Statale 14 - km 163.5 in AREA Science Park, Basovizza, I-34149 Trieste, Italy
| | - Rudi Sergo
- Elettra-Sincrotrone Trieste, Strada Statale 14 - km 163.5 in AREA Science Park, Basovizza, I-34149 Trieste, Italy
| | - Matteo Lucian
- Elettra-Sincrotrone Trieste, Strada Statale 14 - km 163.5 in AREA Science Park, Basovizza, I-34149 Trieste, Italy
| | - Maurizio Barnaba
- Elettra-Sincrotrone Trieste, Strada Statale 14 - km 163.5 in AREA Science Park, Basovizza, I-34149 Trieste, Italy
| | - Tevfik Onur Menteş
- Elettra-Sincrotrone Trieste, Strada Statale 14 - km 163.5 in AREA Science Park, Basovizza, I-34149 Trieste, Italy
| | - Andrea Locatelli
- Elettra-Sincrotrone Trieste, Strada Statale 14 - km 163.5 in AREA Science Park, Basovizza, I-34149 Trieste, Italy.
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Microscopic analysis of the composition driven spin-reorientation transition in Ni(x)Pd(1-x)/Cu(001). Ultramicroscopy 2015; 159 Pt 3:503-7. [PMID: 26092084 DOI: 10.1016/j.ultramic.2015.05.022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Revised: 05/22/2015] [Accepted: 05/28/2015] [Indexed: 11/21/2022]
Abstract
The spin-reorientation transition (SRT) in epitaxial NixPd1-x/Cu(001) is studied by photoemission microscopy utilizing the X-ray magnetic circular dichroism effect at the Ni L2,3 edge. In a composition/thickness wedged geometry, a composition driven SRT could be observed between 37 ML and 60 ML, and 0 and 38% of Pd. Microspectroscopy in combination with azimuthal sample rotation confirms a magnetization preference changing from the [001] to an in-plane easy axis. At this increased thickness, the domain patterns arrange comparable to SRTs in ultrathin films. The images document domains equivalent to a canted state SRT, at which an additional effect of in-plane anisotropies could be identified.
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Patt M, Wiemann C, Weber N, Escher M, Gloskovskii A, Drube W, Merkel M, Schneider CM. Bulk sensitive hard x-ray photoemission electron microscopy. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2014; 85:113704. [PMID: 25430117 DOI: 10.1063/1.4902141] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Hard x-ray photoelectron spectroscopy (HAXPES) has now matured into a well-established technique as a bulk sensitive probe of the electronic structure due to the larger escape depth of the highly energetic electrons. In order to enable HAXPES studies with high lateral resolution, we have set up a dedicated energy-filtered hard x-ray photoemission electron microscope (HAXPEEM) working with electron kinetic energies up to 10 keV. It is based on the NanoESCA design and also preserves the performance of the instrument in the low and medium energy range. In this way, spectromicroscopy can be performed from threshold to hard x-ray photoemission. The high potential of the HAXPEEM approach for the investigation of buried layers and structures has been shown already on a layered and structured SrTiO3 sample. Here, we present results of experiments with test structures to elaborate the imaging and spectroscopic performance of the instrument and show the capabilities of the method to image bulk properties. Additionally, we introduce a method to determine the effective attenuation length of photoelectrons in a direct photoemission experiment.
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Affiliation(s)
- M Patt
- Peter Grünberg Institute (PGI-6) and JARA-FIT, Research Center Jülich, D-52425 Jülich, Germany
| | - C Wiemann
- Peter Grünberg Institute (PGI-6) and JARA-FIT, Research Center Jülich, D-52425 Jülich, Germany
| | - N Weber
- Focus GmbH, Neukirchner Str. 2, D-65510 Hünstetten, Germany
| | - M Escher
- Focus GmbH, Neukirchner Str. 2, D-65510 Hünstetten, Germany
| | - A Gloskovskii
- DESY Photon Science, Deutsches Elektronen-Synchrotron, D-22603 Hamburg, Germany
| | - W Drube
- DESY Photon Science, Deutsches Elektronen-Synchrotron, D-22603 Hamburg, Germany
| | - M Merkel
- Focus GmbH, Neukirchner Str. 2, D-65510 Hünstetten, Germany
| | - C M Schneider
- Peter Grünberg Institute (PGI-6) and JARA-FIT, Research Center Jülich, D-52425 Jülich, Germany
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