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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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Schönhense G, Babenkov S, Vasilyev D, Elmers HJ, Medjanik K. Single-hemisphere photoelectron momentum microscope with time-of-flight recording. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2020; 91:123110. [PMID: 33379996 DOI: 10.1063/5.0024074] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Accepted: 11/26/2020] [Indexed: 06/12/2023]
Abstract
Photoelectron momentum microscopy is an emerging powerful method for angle-resolved photoelectron spectroscopy (ARPES), especially in combination with imaging spin filters. These instruments record kx-ky images, typically exceeding a full Brillouin zone. As energy filters, double-hemispherical or time-of-flight (ToF) devices are in use. Here, we present a new approach for momentum mapping of the full half-space, based on a large single hemispherical analyzer (path radius of 225 mm). Excitation by an unfocused He lamp yielded an energy resolution of 7.7 meV. The performance is demonstrated by k-imaging of quantum-well states in Au and Xe multilayers. The α2-aberration term (α, entrance angle in the dispersive plane) and the transit-time spread of the electrons in the spherical field are studied in a large pass-energy (6 eV-660 eV) and angular range (α up to ±7°). It is discussed how the method circumvents the preconditions of previous theoretical work on the resolution limitation due to the α2-term and the transit-time spread, being detrimental for time-resolved experiments. Thanks to k-resolved detection, both effects can be corrected numerically. We introduce a dispersive-plus-ToF hybrid mode of operation, with an imaging ToF analyzer behind the exit slit of the hemisphere. This instrument captures 3D data arrays I (EB, kx, ky), yielding a gain up to N2 in recording efficiency (N being the number of resolved time slices). A key application will be ARPES at sources with high pulse rates such as synchrotrons with 500 MHz time structure.
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Affiliation(s)
- G Schönhense
- Johannes Gutenberg-Universität, Institut für Physik, 55128 Mainz, Germany
| | - S Babenkov
- Johannes Gutenberg-Universität, Institut für Physik, 55128 Mainz, Germany
| | - D Vasilyev
- Johannes Gutenberg-Universität, Institut für Physik, 55128 Mainz, Germany
| | - H-J Elmers
- Johannes Gutenberg-Universität, Institut für Physik, 55128 Mainz, Germany
| | - K Medjanik
- Johannes Gutenberg-Universität, Institut für Physik, 55128 Mainz, Germany
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3
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Wu B, Wang XD, Gao XF, Li H, Tian SX. Dissociative electron attachment to carbon dioxide. CHINESE J CHEM PHYS 2020. [DOI: 10.1063/1674-0068/cjcp2008152] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Affiliation(s)
- Bin Wu
- Hefei National Laboratory for Physical Sciences at the Microscale, Department of Chemical Physics, University of Science and Technology of China, Hefei 230026, China
| | - Xu-dong Wang
- Hefei National Laboratory for Physical Sciences at the Microscale, Department of Chemical Physics, University of Science and Technology of China, Hefei 230026, China
| | - Xiao-fei Gao
- Hefei National Laboratory for Physical Sciences at the Microscale, Department of Chemical Physics, University of Science and Technology of China, Hefei 230026, China
| | - Hao Li
- Hefei National Laboratory for Physical Sciences at the Microscale, Department of Chemical Physics, University of Science and Technology of China, Hefei 230026, China
| | - Shan Xi Tian
- Hefei National Laboratory for Physical Sciences at the Microscale, Department of Chemical Physics, University of Science and Technology of China, Hefei 230026, China
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Mingels S, Porshyn V, Bornmann B, Lützenkirchen-Hecht D, Müller G. Sensitive fast electron spectrometer in adjustable triode configuration with pulsed tunable laser for research on photo-induced field emission cathodes. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2015; 86:043307. [PMID: 25933855 DOI: 10.1063/1.4919011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We have completed an ultra-high vacuum system for sensitive fast electron spectroscopy from cold cathodes in triode configuration under high electric fields E (<100 MV/m) and pulsed tunable laser illumination (3.5 ns, 10 Hz, hν = 0.5-5.9 eV, and 0.3-17 mJ). The cathodes are prepared and inserted under clean room conditions and can be precisely 3D-positioned, cooled or heated (77-400 K). Commissioning results with the upgraded system are presented. Field emission measurements with a W tip yielded an energy resolution of 14 meV at 4 eV pass energy and a precise determination of the emitter work function, size, and temperature. Photoemission spectroscopy of short electron bunches from a virgin and laser-ablated S-GaP crystal and quantum efficiency measurements revealed surface states, energy relaxation, and band structure effects. In conclusion, this novel system is ready now for the development and characterization of photo-induced field emission cathodes.
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Affiliation(s)
- S Mingels
- FB C Physics Department, University of Wuppertal, 42119 Wuppertal, Germany
| | - V Porshyn
- FB C Physics Department, University of Wuppertal, 42119 Wuppertal, Germany
| | - B Bornmann
- FB C Physics Department, University of Wuppertal, 42119 Wuppertal, Germany
| | | | - G Müller
- FB C Physics Department, University of Wuppertal, 42119 Wuppertal, Germany
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Menteş TO, Zamborlini G, Sala A, Locatelli A. Cathode lens spectromicroscopy: methodology and applications. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2014; 5:1873-86. [PMID: 25383299 PMCID: PMC4222408 DOI: 10.3762/bjnano.5.198] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Accepted: 09/25/2014] [Indexed: 05/28/2023]
Abstract
The implementation of imaging techniques with low-energy electrons at synchrotron laboratories allowed for significant advancement in the field of spectromicroscopy. The spectroscopic photoemission and low energy electron microscope, SPELEEM, is a notable example. We summarize the multitechnique capabilities of the SPELEEM instrument, reporting on the instrumental aspects and the latest developments on the technical side. We briefly review applications, which are grouped into two main scientific fields. The first one covers different aspects of graphene physics. In particular, we highlight the recent work on graphene/Ir(100). Here, SPELEEM was employed to monitor the changes in the electronic structure that occur for different film morphologies and during the intercalation of Au. The Au monolayer, which creeps under graphene from the film edges, efficiently decouples the graphene from the substrate lowering the Dirac energy from 0.42 eV to 0.1 eV. The second field combines magnetism studies at the mesoscopic length scale with self-organized systems featuring ordered nanostructures. This example highlights the possibility to monitor growth processes in real time and combine chemical characterization with X-ray magnetic circular dichroism-photoemission electron microscopy (XMCD-PEEM) magnetic imaging by using the variable photon polarization and energy available at the synchrotron source.
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Affiliation(s)
- T O Menteş
- Elettra - Sincrotrone Trieste S.C.p.A., Basovizza, Trieste 34149, Italy
| | - G Zamborlini
- Department of Physics, University of Trieste, Via Valerio 2, Trieste 34137, Italy
- Peter Grünberg Institute (PGI-6) and JARA-FIT, Research Center Jülich, 52425 Jülich, Germany
| | - A Sala
- Elettra - Sincrotrone Trieste S.C.p.A., Basovizza, Trieste 34149, Italy
| | - A Locatelli
- Elettra - Sincrotrone Trieste S.C.p.A., Basovizza, Trieste 34149, Italy
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Bornmann B, Mingels S, Dams F, Prommesberger C, Schreiner R, Lützenkirchen-Hecht D, Müller G. Electron spectrometer in adjustable triode configuration for photo-induced field emission measurements. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2012; 83:013302. [PMID: 22299940 DOI: 10.1063/1.3673475] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We have constructed a new ultrahigh vacuum apparatus with a triode configuration for the systematic investigation of photo-induced field emission (PFE) from metallic or semiconducting cathodes. These are exposed to electric fields up to 400 MV∕m and laser irradiation by means of hole or mesh gates. Cathodes and gates are in situ exchangeable and adjustable with high precision to ensure a homogeneous extraction of electrons which are partially transmitted to the fixed electron spectrometer. Its hemispherical sector analyzer provides an energy resolution limit of 8 meV. The commissioning of the measurement system has been performed with a tungsten needle. Its temperature showed up in the high-energy tail of the electron spectrum, while its work function was derived from the spectral low-energy part combined with the integral current-voltage curve. First PFE measurements on B-doped Si-tip arrays yielded a small field emission current increase under green laser illumination. A shift and splitting of the energy spectra was observed which revealed different emission regimes as well as the photosensitivity of the cathode due to carrier excitation into the conduction band. For the full exploitation of the PFE system, a tunable laser over a wide eV-range is required.
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Affiliation(s)
- B Bornmann
- FB C Physics Department, University of Wuppertal, Wuppertal, Germany.
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Jozwiak C, Graf J, Lebedev G, Andresen N, Schmid AK, Fedorov AV, El Gabaly F, Wan W, Lanzara A, Hussain Z. A high-efficiency spin-resolved photoemission spectrometer combining time-of-flight spectroscopy with exchange-scattering polarimetry. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2010; 81:053904. [PMID: 20515152 DOI: 10.1063/1.3427223] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
We describe a spin-resolved electron spectrometer capable of uniquely efficient and high energy resolution measurements. Spin analysis is obtained through polarimetry based on low-energy exchange scattering from a ferromagnetic thin-film target. This approach can achieve a similar analyzing power (Sherman function) as state-of-the-art Mott scattering polarimeters, but with as much as 100 times improved efficiency due to increased reflectivity. Performance is further enhanced by integrating the polarimeter into a time-of-flight (TOF) based energy analysis scheme with a precise and flexible electrostatic lens system. The parallel acquisition of a range of electron kinetic energies afforded by the TOF approach results in an order of magnitude (or more) increase in efficiency compared to hemispherical analyzers. The lens system additionally features a 90 degrees bandpass filter, which by removing unwanted parts of the photoelectron distribution allows the TOF technique to be performed at low electron drift energy and high energy resolution within a wide range of experimental parameters. The spectrometer is ideally suited for high-resolution spin- and angle-resolved photoemission spectroscopy (spin-ARPES), and initial results are shown. The TOF approach makes the spectrometer especially ideal for time-resolved spin-ARPES experiments.
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Affiliation(s)
- C Jozwiak
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
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Bruhns H, Kreckel H, Miller K, Lestinsky M, Seredyuk B, Mitthumsiri W, Schmitt BL, Schnell M, Urbain X, Rappaport ML, Havener CC, Savin DW. A novel merged beams apparatus to study anion-neutral reactions. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2010; 81:013112. [PMID: 20113086 DOI: 10.1063/1.3280227] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2009] [Accepted: 12/08/2009] [Indexed: 05/28/2023]
Abstract
We have developed a novel laboratory instrument for studying gas phase, anion-neutral chemistry. To the best of our knowledge, this is the first such apparatus which uses fast merged beams to investigate anion-neutral chemical reactions. As proof-of-principle we have detected the associative detachment reaction H(-)+H-->H(2)+e(-). Here we describe the apparatus in detail and discuss related technical and experimental issues.
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Affiliation(s)
- H Bruhns
- Columbia Astrophysics Laboratory, Columbia University, New York, New York 10027-6601, USA
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9
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Krömker B, Escher M, Funnemann D, Hartung D, Engelhard H, Kirschner J. Development of a momentum microscope for time resolved band structure imaging. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2008; 79:053702. [PMID: 18513070 DOI: 10.1063/1.2918133] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
We demonstrate the use of a novel design of a photoelectron microscope in combination to an imaging energy filter for momentum resolved photoelectron detection. Together with a time resolved imaging detector, it is possible to combine spatial, momentum, energy, and time resolution of photoelectrons within the same instrument. The time resolution of this type of energy analyzer can be reduced to below 100 ps. The complete ARUPS pattern of a Cu(111) sample excited with He I, is imaged in parallel and energy resolved up to the photoelectron emission horizon. Excited with a mercury light source (h nu=4.9 eV), the Shockley surface state at the energy threshold is clearly imaged in k-space. Electron-electron interactions are observed in momentum space as a correlation hole in two-electron photoemission. With the high transmission and the time resolution of this instrument, possible new measurements are discussed: Time and polarization resolved ARUPS measurements, probing change of bandstructure due to chemical reaction, growth of films, or phase transitions, e.g., melting or martensitic transformations.
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Affiliation(s)
- B Krömker
- Omicron Nanotechnology GmbH, 65232 Taunusstein, GermanyFocus GmbH, 65510 Hünstetten, Germany
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10
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Dogan M, Sise O, Ulu M. Design of electron energy analyzers for electron impact studies. Radiat Phys Chem Oxf Engl 1993 2007. [DOI: 10.1016/j.radphyschem.2006.01.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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12
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Poulin A, Roy D. Optimisation of the 180 degrees hemispherical electrostatic deflector. ACTA ACUST UNITED AC 2001. [DOI: 10.1088/0022-3735/11/1/009] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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13
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van VM, den HS. Transmission of through-the-lens Auger spectroscopy in an electron microscope. Ultramicroscopy 2001; 90:113-9. [PMID: 11942631 DOI: 10.1016/s0304-3991(01)00142-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
In this paper, the transmission properties of through-the-lens Auger spectroscopy in an electron microscope using an electro-magnetic immersion lens are calculated. The effects of changes in acceptance angle and entrance slit of the spectrometer are discussed. It is shown that by including the effects of oscillations in final angle and radius, enhanced transmission is obtained under typical experimental conditions.
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Affiliation(s)
- V M van
- Philips Research Laboratories, Eindhoven, The Netherlands
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14
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Wilden DG, Hicks PJ, Comer J. Autoionization of N2studied using an electron time-of-flight coincidence spectrometer. ACTA ACUST UNITED AC 2001. [DOI: 10.1088/0022-3700/9/11/022] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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15
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Hollywood MT, Crowe A, Williams JF. Coherent excitation of the 21P state of He for large momentum transfer electron scattering. ACTA ACUST UNITED AC 2001. [DOI: 10.1088/0022-3700/12/5/026] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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16
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Volkel M, Sandner W. Optimisation of electron energy analysers for application in coincidence experiments. ACTA ACUST UNITED AC 2000. [DOI: 10.1088/0022-3735/16/5/020] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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17
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Wincott PL, Brookes NB, Law DSL, Thornton G, King GC. Design and performance of a high-resolution electron energy analyser for angle-resolved photoemission spectroscopy. ACTA ACUST UNITED AC 2000. [DOI: 10.1088/0022-3735/22/1/009] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Cornay DJ, King GC, Buckman SJ. Lifetime measurements of VUV emitting levels in He, Ne, Ar and CO using the inelastic electron-photon delayed coincidence technique. ACTA ACUST UNITED AC 1999. [DOI: 10.1088/0022-3700/17/15/028] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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20
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Schuppler S, Fischer N, Fauster T, Steinmann W. Lifetime of image-potential states on metal surfaces. PHYSICAL REVIEW. B, CONDENSED MATTER 1992; 46:13539-13547. [PMID: 10003401 DOI: 10.1103/physrevb.46.13539] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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21
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Magnetic Through-the-lens Detection in Electron Microscopy and Spectroscopy, Part 1. ACTA ACUST UNITED AC 1991. [DOI: 10.1016/b978-0-12-029912-6.50007-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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22
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Brunger MJ, Teubner PJ. Differential cross sections for electron-impact excitation of the electronic states of N2. PHYSICAL REVIEW. A, ATOMIC, MOLECULAR, AND OPTICAL PHYSICS 1990; 41:1413-1426. [PMID: 9903236 DOI: 10.1103/physreva.41.1413] [Citation(s) in RCA: 89] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/11/2023]
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23
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24
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Johnson LP, Morrison JD, Wahrhaftig AL. Electrostatic electron energy analysers and the application of the cylindrical mirror system to the study of ionization efficiencies by electron impact. ACTA ACUST UNITED AC 1978. [DOI: 10.1016/0020-7381(78)80001-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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