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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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2
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Casavola AR, Cartoni A, Castrovilli MC, Borocci S, Bolognesi P, Chiarinelli J, Catone D, Avaldi L. VUV Photofragmentation of Chloroiodomethane: The Iso-CH 2I-Cl and Iso-CH 2Cl-I Radical Cation Formation. J Phys Chem A 2020; 124:7491-7499. [PMID: 32786965 PMCID: PMC8010789 DOI: 10.1021/acs.jpca.0c05754] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
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Dihalomethanes
XCH2Y (X and Y = F, Cl, Br, and I) are a class of compounds
involved in several processes leading to the release of halogen atoms,
ozone consumption, and aerosol particle formation. Neutral dihalomethanes
have been largely studied, but chemical physics properties and processes
involving their radical ions, like the pathways of their decomposition,
have not been completely investigated. In this work the photodissociation
dynamics of the ClCH2I molecule has been explored in the
photon energy range 9–21 eV using both VUV rare gas discharge
lamps and synchrotron radiation. The experiments show that, among
the different fragment ions, CH2I+ and CH2Cl+, which correspond to the Cl- and I-losses,
respectively, play a dominant role. The experimental ionization energy
of ClCH2I and the appearance energies of the CH2I+ and CH2Cl+ ions are in agreement
with the theoretical results obtained at the MP2/CCSD(T) level of
theory. Computational investigations have been also performed to study
the isomerization of geminal [ClCH2I]•+ into the iso-chloroiodomethane isomers: [CH2I–Cl]•+ and [CH2Cl–I]•+.
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Affiliation(s)
- Anna Rita Casavola
- Institute of Structure of Matter-CNR (ISM-CNR), Area della Ricerca di Roma 1, Via Salaria km 29.300, 00015 Monterotondo, Italy
| | - Antonella Cartoni
- Institute of Structure of Matter-CNR (ISM-CNR), Area della Ricerca di Roma 1, Via Salaria km 29.300, 00015 Monterotondo, Italy.,Department of Chemistry, Sapienza University of Rome, P.le Aldo Moro 5, 00185 Rome, Italy
| | - Mattea Carmen Castrovilli
- Institute of Structure of Matter-CNR (ISM-CNR), Area della Ricerca di Roma 1, Via Salaria km 29.300, 00015 Monterotondo, Italy
| | - Stefano Borocci
- Department for Innovation in Biological, Agrofood and Forest Systems, University of Tuscia, Viterbo 01100, Italy.,Institute for Biological Systems-CNR (ISB-CNR), Area della Ricerca di Roma 1, Via Salaria, Km 29.500,, 00015 Monterotondo, Italy
| | - Paola Bolognesi
- Institute of Structure of Matter-CNR (ISM-CNR), Area della Ricerca di Roma 1, Via Salaria km 29.300, 00015 Monterotondo, Italy
| | - Jacopo Chiarinelli
- Institute of Structure of Matter-CNR (ISM-CNR), Area della Ricerca di Roma 1, Via Salaria km 29.300, 00015 Monterotondo, Italy
| | - Daniele Catone
- Institute of Structure of Matter-CNR (ISM-CNR), Area della Ricerca di Tor Vergata, Via del Fosso del Cavaliere, 00133 Rome, Italy
| | - Lorenzo Avaldi
- Institute of Structure of Matter-CNR (ISM-CNR), Area della Ricerca di Roma 1, Via Salaria km 29.300, 00015 Monterotondo, Italy
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Chiarinelli J, Markus P, Bolognesi P, Avaldi L, Turco Liveri V, Calandra P. Photo-fragmentation of alkyl phosphates in the gas-phase. J Photochem Photobiol A Chem 2018. [DOI: 10.1016/j.jphotochem.2018.07.017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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4
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Plötzing M, Adam R, Weier C, Plucinski L, Eich S, Emmerich S, Rollinger M, Aeschlimann M, Mathias S, Schneider CM. Spin-resolved photoelectron spectroscopy using femtosecond extreme ultraviolet light pulses from high-order harmonic generation. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2016; 87:043903. [PMID: 27131684 DOI: 10.1063/1.4946782] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
The fundamental mechanism responsible for optically induced magnetization dynamics in ferromagnetic thin films has been under intense debate since almost two decades. Currently, numerous competing theoretical models are in strong need for a decisive experimental confirmation such as monitoring the triggered changes in the spin-dependent band structure on ultrashort time scales. Our approach explores the possibility of observing femtosecond band structure dynamics by giving access to extended parts of the Brillouin zone in a simultaneously time-, energy- and spin-resolved photoemission experiment. For this purpose, our setup uses a state-of-the-art, highly efficient spin detector and ultrashort, extreme ultraviolet light pulses created by laser-based high-order harmonic generation. In this paper, we present the setup and first spin-resolved spectra obtained with our experiment within an acquisition time short enough to allow pump-probe studies. Further, we characterize the influence of the excitation with femtosecond extreme ultraviolet pulses by comparing the results with data acquired using a continuous wave light source with similar photon energy. In addition, changes in the spectra induced by vacuum space-charge effects due to both the extreme ultraviolet probe- and near-infrared pump-pulses are studied by analyzing the resulting spectral distortions. The combination of energy resolution and electron count rate achieved in our setup confirms its suitability for spin-resolved studies of the band structure on ultrashort time scales.
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Affiliation(s)
- M Plötzing
- Forschungszentrum Jülich GmbH, Peter Grünberg Institut (PGI-6), 52425 Jülich, Germany
| | - R Adam
- Forschungszentrum Jülich GmbH, Peter Grünberg Institut (PGI-6), 52425 Jülich, Germany
| | - C Weier
- Forschungszentrum Jülich GmbH, Peter Grünberg Institut (PGI-6), 52425 Jülich, Germany
| | - L Plucinski
- Forschungszentrum Jülich GmbH, Peter Grünberg Institut (PGI-6), 52425 Jülich, Germany
| | - S Eich
- University of Kaiserslautern and Research Center OPTIMAS, 67663 Kaiserslautern, Germany
| | - S Emmerich
- University of Kaiserslautern and Research Center OPTIMAS, 67663 Kaiserslautern, Germany
| | - M Rollinger
- University of Kaiserslautern and Research Center OPTIMAS, 67663 Kaiserslautern, Germany
| | - M Aeschlimann
- University of Kaiserslautern and Research Center OPTIMAS, 67663 Kaiserslautern, Germany
| | - S Mathias
- Georg-August-Universität Göttingen, I. Physikalisches Institut, 37077 Göttingen, Germany
| | - C M Schneider
- Forschungszentrum Jülich GmbH, Peter Grünberg Institut (PGI-6), 52425 Jülich, Germany
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5
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Cartoni A, Bolognesi P, Fainelli E, Avaldi L. Photofragmentation spectra of halogenated methanes in the VUV photon energy range. J Chem Phys 2014; 140:184307. [PMID: 24832270 DOI: 10.1063/1.4874114] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
In this paper an investigation of the photofragmentation of dihalomethanes CH2X2 (X = F, Cl, Br, I) and chlorinated methanes (CH(n)Cl(4-n) with n = 0-3) with VUV helium, neon, and argon discharge lamps is reported and the role played by the different halogen atoms is discussed. Halogenated methanes are a class of molecules used in several fields of chemistry and the study of their physical and chemical proprieties is of fundamental interest. In particular their photodissociation and photoionization are of great importance since the decomposition of these compounds in the atmosphere strongly affects the environment. The results of the present work show that the halogen-loss is the predominant fragmentation channel for these molecules in the VUV photon energy range and confirm their role as reservoir of chlorine, bromine, and iodine atoms in the atmosphere. Moreover, the results highlight the peculiar feature of CH2F2 as a source of both fluorine and hydrogen atoms and the characteristic formation of I2(+) and CH2(+) ions from the photofragmentation of the CH2I2 molecule.
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Affiliation(s)
- Antonella Cartoni
- Dipartimento di Chimica e Tecnologie del Farmaco, Sapienza Università di Roma, P.le Aldo Moro 5, Roma 00185, Italy
| | - Paola Bolognesi
- CNR-IMIP, Area della Ricerca di Roma 1, Monterotondo Scalo (Rm) 00015, Italy
| | - Ettore Fainelli
- CNR-IMIP, Area della Ricerca di Roma 1, Monterotondo Scalo (Rm) 00015, Italy
| | - Lorenzo Avaldi
- CNR-IMIP, Area della Ricerca di Roma 1, Monterotondo Scalo (Rm) 00015, Italy
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Roberts FS, Anderson SL. Note: Hollow cathode lamp with integral, high optical efficiency isolation valve: a modular vacuum ultraviolet source. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2013; 84:126101. [PMID: 24387477 DOI: 10.1063/1.4838675] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The design and operating conditions of a hollow cathode discharge lamp for the generation of vacuum ultraviolet radiation, suitable for ultrahigh vacuum (UHV) application, are described in detail. The design is easily constructed, and modular, allowing it to be adapted to different experimental requirements. A thin isolation valve is built into one of the differential pumping stages, isolating the discharge section from the UHV section, both for vacuum safety and to allow lamp maintenance without venting the UHV chamber. The lamp has been used both for ultraviolet photoelectron spectroscopy of surfaces and as a "soft" photoionization source for gas-phase mass spectrometry.
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Affiliation(s)
- F Sloan Roberts
- Department of Chemistry, University of Utah, 315 S. 1400 E., Salt Lake City, Utah 84112, USA
| | - Scott L Anderson
- Department of Chemistry, University of Utah, 315 S. 1400 E., Salt Lake City, Utah 84112, USA
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Lukic S, Bornschein B, Drexlin G, Glück F, Kazachenko O, Schöppner M, Weinheimer C, Zoll MCR. Ion source for tests of ion behavior in the Karlsruhe tritium neutrino experiment beam line. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2011; 82:013303. [PMID: 21280821 DOI: 10.1063/1.3504372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
An electron-impact ion source based on photoelectron emission was developed for ionization of gases at pressures below 10(-4) mbar in an axial magnetic field in the order of 5 T. The ion source applies only dc fields, which makes it suitable for use in the presence of equipment sensitive to radio-frequency (RF) fields. The ion source was successfully tested under varying conditions regarding pressure, magnetic field, and magnetic-field gradient, and the results were studied with the help of simulations. The processes in the ion source are well understood, and possibilities for further optimization of generated ion currents are clarified.
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Affiliation(s)
- S Lukic
- Karlsruhe Institute of Technology, Germany.
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Getzlaff M, Bansmann J, Schönhense G. CO interactions with ferromagnetic surfaces. J Chem Phys 1995. [DOI: 10.1063/1.470399] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Stoppmanns P, Heidemann B, Irmer N, Müller N, Vogt B, Schmiedeskamp B, Heinzmann U, Tamura E, Feder R. Au-induced surface state on Pt(111) revealed by spin-resolved photoemission with linearly polarized light. PHYSICAL REVIEW LETTERS 1991; 66:2645-2648. [PMID: 10043575 DOI: 10.1103/physrevlett.66.2645] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Kaesdorf S, Schönhense G, Heinzmann U. Experimental angular-resolved photoelectron spectroscopy of free oriented CH3I molecules. PHYSICAL REVIEW LETTERS 1985; 54:885-888. [PMID: 10031646 DOI: 10.1103/physrevlett.54.885] [Citation(s) in RCA: 35] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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