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Rosi P, Clausen A, Weber D, Tavabi AH, Frabboni S, Tiemeijer P, Dunin-Borkowski RE, Rotunno E, Grillo V. Automatic Alignment of an Orbital Angular Momentum Sorter in a Transmission Electron Microscope Using a Convolutional Neural Network. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2022; 29:1-9. [PMID: 36082682 DOI: 10.1017/s143192762201248x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
We report on the automatic alignment of a transmission electron microscope equipped with an orbital angular momentum sorter using a convolutional neural network. The neural network is able to control all relevant parameters of both the electron-optical setup of the microscope and the external voltage source of the sorter without input from the user. It can compensate for mechanical and optical misalignments of the sorter, in order to optimize its spectral resolution. The alignment is completed over a few frames and can be kept stable by making use of the fast fitting time of the neural network.
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Affiliation(s)
- Paolo Rosi
- Istituto Nanoscienze - CNR, via G. Campi 213/A, Modena 41125, Italy
- FIM Department, University of Modena and Reggio Emilia, via G. Campi 213/A, Modena 41125, Italy
| | - Alexander Clausen
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Forschungszentrum Jülich, Jülich 52425, Germany
| | - Dieter Weber
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Forschungszentrum Jülich, Jülich 52425, Germany
| | - Amir H Tavabi
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Forschungszentrum Jülich, Jülich 52425, Germany
| | - Stefano Frabboni
- Istituto Nanoscienze - CNR, via G. Campi 213/A, Modena 41125, Italy
- FIM Department, University of Modena and Reggio Emilia, via G. Campi 213/A, Modena 41125, Italy
| | - Peter Tiemeijer
- Thermo Fisher Scientific, PO Box 80066, 5600 KA Eindhoven, The Netherlands
| | - Rafal E Dunin-Borkowski
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Forschungszentrum Jülich, Jülich 52425, Germany
| | - Enzo Rotunno
- Istituto Nanoscienze - CNR, via G. Campi 213/A, Modena 41125, Italy
| | - Vincenzo Grillo
- Istituto Nanoscienze - CNR, via G. Campi 213/A, Modena 41125, Italy
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Tavabi AH, Rosi P, Rotunno E, Roncaglia A, Belsito L, Frabboni S, Pozzi G, Gazzadi GC, Lu PH, Nijland R, Ghosh M, Tiemeijer P, Karimi E, Dunin-Borkowski RE, Grillo V. Experimental Demonstration of an Electrostatic Orbital Angular Momentum Sorter for Electron Beams. PHYSICAL REVIEW LETTERS 2021; 126:094802. [PMID: 33750150 DOI: 10.1103/physrevlett.126.094802] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Revised: 12/06/2020] [Accepted: 01/12/2021] [Indexed: 05/21/2023]
Abstract
The component of orbital angular momentum (OAM) in the propagation direction is one of the fundamental quantities of an electron wave function that describes its rotational symmetry and spatial chirality. Here, we demonstrate experimentally an electrostatic sorter that can be used to analyze the OAM states of electron beams in a transmission electron microscope. The device achieves postselection or sorting of OAM states after electron-material interactions, thereby allowing the study of new material properties such as the magnetic states of atoms. The required electron-optical configuration is achieved by using microelectromechanical systems technology and focused ion beam milling to control the electron phase electrostatically with a lateral resolution of 50 nm. An OAM resolution of 1.5ℏ is realized in tests on controlled electron vortex beams, with the perspective of reaching an optimal OAM resolution of 1ℏ in the near future.
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Affiliation(s)
- Amir H Tavabi
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Paolo Rosi
- Dipartimento FIM, Universitá di Modena e Reggio Emilia, 41125 Modena, Italy
| | - Enzo Rotunno
- Centro S3, Istituto di Nanoscienze-CNR, 41125 Modena, Italy
| | - Alberto Roncaglia
- Istituto per la Microelettronica e i Microsistemi-CNR, 40129 Bologna, Italy
| | - Luca Belsito
- Istituto per la Microelettronica e i Microsistemi-CNR, 40129 Bologna, Italy
| | - Stefano Frabboni
- Dipartimento FIM, Universitá di Modena e Reggio Emilia, 41125 Modena, Italy
- Centro S3, Istituto di Nanoscienze-CNR, 41125 Modena, Italy
| | - Giulio Pozzi
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, 52425 Jülich, Germany
- Department of Physics and Astronomy, University of Bologna, 40127 Bologna, Italy
| | | | - Peng-Han Lu
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, 52425 Jülich, Germany
- RWTH Aachen University, 52074 Aachen, Germany
| | - Robert Nijland
- Thermo Fisher Scientific, PO Box 80066, 5600 KA Eindhoven, Netherlands
| | - Moumita Ghosh
- Thermo Fisher Scientific, PO Box 80066, 5600 KA Eindhoven, Netherlands
| | - Peter Tiemeijer
- Thermo Fisher Scientific, PO Box 80066, 5600 KA Eindhoven, Netherlands
| | - Ebrahim Karimi
- Department of Physics, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada
| | - Rafal E Dunin-Borkowski
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, 52425 Jülich, Germany
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Guido CA, Rotunno E, Zanfrognini M, Corni S, Grillo V. Exploring the Spatial Features of Electronic Transitions in Molecular and Biomolecular Systems by Swift Electrons. J Chem Theory Comput 2021; 17:2364-2373. [PMID: 33646769 PMCID: PMC8047794 DOI: 10.1021/acs.jctc.1c00045] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
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We
devise a new kind of experiment that extends the technology
of electron energy loss spectroscopy to probe (supra-)molecular systems: by using
an electron beam in a configuration that avoids
molecular damage and a very recently introduced electron optics setup
for the analysis of the outcoming electrons, one can obtain information
on the spatial features of the investigated excitations. Physical
insight into the proposed experiment is provided by means of a simple
but rigorous model to obtain the transition rate and selection rule.
Numerical simulations of DNA G-quadruplexes and other biomolecular
systems, based on time dependent density functional theory calculations,
point out that the conceived new technique can probe the multipolar
components and even the chirality of molecular transitions, superseding
the usual optical spectroscopies for those cases that are problematic,
such as dipole-forbidden transitions, at a very high spatial resolution.
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Affiliation(s)
- Ciro A Guido
- Dipartimento di Scienze Chimiche, Università di Padova, via F. Marzolo 1, 35131 Padova, Italy
| | - Enzo Rotunno
- CNR-NANO, Institute of Nanoscience, via Campi 213/A, Modena, Italy
| | | | - Stefano Corni
- Dipartimento di Scienze Chimiche, Università di Padova, via F. Marzolo 1, 35131 Padova, Italy.,CNR-NANO, Institute of Nanoscience, via Campi 213/A, Modena, Italy
| | - Vincenzo Grillo
- CNR-NANO, Institute of Nanoscience, via Campi 213/A, Modena, Italy
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Zhang K, Yuan Y, Zhang D, Ding X, Ratni B, Burokur SN, Lu M, Tang K, Wu Q. Phase-engineered metalenses to generate converging and non-diffractive vortex beam carrying orbital angular momentum in microwave region. OPTICS EXPRESS 2018; 26:1351-1360. [PMID: 29402010 DOI: 10.1364/oe.26.001351] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Accepted: 01/09/2018] [Indexed: 06/07/2023]
Abstract
In this paper, ultra-thin metalenses are proposed to generate converging and non-diffractive vortex beam carrying orbital angular momentum (OAM) in microwave region. Phase changes are introduced to the transmission cross-polarized wave by tailoring spatial orientation of Pancharatnam-Berry phase unit cell. Based on the superposition of phase profile of spiral phase plate and that of a converging lens or an axicon, vortex beam carrying OAM mode generated by the metalens can also exhibit characteristics of a focusing beam or a Bessel beam. Measured field intensities and phase distributions at microwave frequencies verify the theoretical design procedure. The proposed method provides an efficient approach to control the radius of vortex beam carrying OAM mode in microwave wireless applications for medium-short range distance.
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van Kruining K, Hayrapetyan AG, Götte JB. Nonuniform Currents and Spins of Relativistic Electron Vortices in a Magnetic Field. PHYSICAL REVIEW LETTERS 2017; 119:030401. [PMID: 28777634 DOI: 10.1103/physrevlett.119.030401] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Indexed: 06/07/2023]
Abstract
We present a relativistic description of electron vortex beams in a homogeneous magnetic field. Including spin from the beginning reveals that spin-polarized electron vortex beams have a complicated azimuthal current structure, containing small rings of counterrotating current between rings of stronger corotating current. Contrary to many other problems in relativistic quantum mechanics, there exists a set of vortex beams with exactly zero spin-orbit mixing in the highly relativistic and nonparaxial regime. The well-defined phase structure of these beams is analogous to simpler scalar vortex beams, owing to the protection by the Zeeman effect. For states that do show spin-orbit mixing, the spin polarization across the beam is nonuniform rendering the spin and orbital degrees of freedom inherently inseparable.
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Affiliation(s)
- Koen van Kruining
- Max-Planck-Institut für Physik komplexer Systeme, 01187 Dresden, Germany
| | | | - Jörg B Götte
- Nanjing University, Nanjing 210093, China
- University of Glasgow, Glasgow G12 8QQ, United Kingdom
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Bialynicki-Birula I, Bialynicka-Birula Z. Relativistic Electron Wave Packets Carrying Angular Momentum. PHYSICAL REVIEW LETTERS 2017; 118:114801. [PMID: 28368650 DOI: 10.1103/physrevlett.118.114801] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Indexed: 06/07/2023]
Abstract
There are important differences between the nonrelativistic and relativistic description of electron beams. In the relativistic case the orbital angular momentum quantum number cannot be used to specify the wave functions and the structure of vortex lines in these two descriptions is completely different. We introduce analytic solutions of the Dirac equation in the form of exponential wave packets and we argue that they properly describe relativistic electron beams carrying angular momentum.
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Affiliation(s)
- Iwo Bialynicki-Birula
- Center for Theoretical Physics, Polish Academy of Sciences, Aleja Lotników 32/46, 02-668 Warsaw, Poland
| | - Zofia Bialynicka-Birula
- Institute of Physics, Polish Academy of Sciences, Aleja Lotników 32/46, 02-668 Warsaw, Poland
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